spl: mmc: remove #ifdef CONFIG_SPL_OS_BOOT check

Implement default versions of falcon mode functions to make the
CONFIG_SPL_OS_BOOT check in spl_mmc_load_image() unnecessary, thus reducing
its #ifdef complexity.

No functional changes.

Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Cc: Paul Kocialkowski <contact@paulk.fr>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Guillaume GARDET <guillaume.gardet@free.fr>
Cc: Suriyan Ramasami <suriyan.r@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/common/spl/spl_ext.c b/common/spl/spl_ext.c
index 9d37fd3..a42fbd0 100644
--- a/common/spl/spl_ext.c
+++ b/common/spl/spl_ext.c
@@ -6,6 +6,7 @@
 #include <spl.h>
 #include <asm/u-boot.h>
 #include <ext4fs.h>
+#include <errno.h>
 #include <image.h>
 
 #ifdef CONFIG_SPL_EXT_SUPPORT
@@ -135,5 +136,10 @@
 	return spl_load_image_ext(block_dev, partition,
 			CONFIG_SPL_FS_LOAD_KERNEL_NAME);
 }
+#else
+int spl_load_image_ext_os(block_dev_desc_t *block_dev, int partition)
+{
+	return -ENOSYS;
+}
 #endif
 #endif
diff --git a/common/spl/spl_fat.c b/common/spl/spl_fat.c
index 350f7d9..0daadbe 100644
--- a/common/spl/spl_fat.c
+++ b/common/spl/spl_fat.c
@@ -13,6 +13,7 @@
 #include <spl.h>
 #include <asm/u-boot.h>
 #include <fat.h>
+#include <errno.h>
 #include <image.h>
 
 static int fat_registered;
@@ -119,5 +120,10 @@
 	return spl_load_image_fat(block_dev, partition,
 			CONFIG_SPL_FS_LOAD_KERNEL_NAME);
 }
+#else
+int spl_load_image_fat_os(block_dev_desc_t *block_dev, int partition)
+{
+	return -ENOSYS;
+}
 #endif
 #endif
diff --git a/common/spl/spl_mmc.c b/common/spl/spl_mmc.c
index 9d3c09e..837fa0d 100644
--- a/common/spl/spl_mmc.c
+++ b/common/spl/spl_mmc.c
@@ -154,6 +154,15 @@
 	return mmc_load_image_raw_sector(mmc,
 		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR);
 }
+#else
+int spl_start_uboot(void)
+{
+	return 1;
+}
+static int mmc_load_image_raw_os(struct mmc *mmc)
+{
+	return -ENOSYS;
+}
 #endif
 
 void spl_mmc_load_image(void)
@@ -179,13 +188,11 @@
 	case MMCSD_MODE_RAW:
 		debug("spl: mmc boot mode: raw\n");
 
-#ifdef CONFIG_SPL_OS_BOOT
 		if (!spl_start_uboot()) {
 			err = mmc_load_image_raw_os(mmc);
 			if (!err)
 				return;
 		}
-#endif
 #if defined(CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION)
 		err = mmc_load_image_raw_partition(mmc,
 			CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION);
@@ -203,14 +210,12 @@
 
 #ifdef CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
 #ifdef CONFIG_SPL_FAT_SUPPORT
-#ifdef CONFIG_SPL_OS_BOOT
 		if (!spl_start_uboot()) {
 			err = spl_load_image_fat_os(&mmc->block_dev,
 				CONFIG_SYS_MMCSD_FS_BOOT_PARTITION);
 			if (!err)
 				return;
 		}
-#endif
 #ifdef CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
 		err = spl_load_image_fat(&mmc->block_dev,
 					 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION,
@@ -220,14 +225,12 @@
 #endif
 #endif
 #ifdef CONFIG_SPL_EXT_SUPPORT
-#ifdef CONFIG_SPL_OS_BOOT
 		if (!spl_start_uboot()) {
 			err = spl_load_image_ext_os(&mmc->block_dev,
 				CONFIG_SYS_MMCSD_FS_BOOT_PARTITION);
 			if (!err)
 				return;
 		}
-#endif
 #ifdef CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
 		err = spl_load_image_ext(&mmc->block_dev,
 					 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION,
@@ -257,13 +260,11 @@
 			hang();
 		}
 
-#ifdef CONFIG_SPL_OS_BOOT
 		if (!spl_start_uboot()) {
 			err = mmc_load_image_raw_os(mmc);
 			if (!err)
 				return;
 		}
-#endif
 #if defined(CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION)
 		err = mmc_load_image_raw_partition(mmc,
 			CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION);