Rename some defines containing FAT in their name to be filesystem generic

Rename some defines containing FAT in their name to be filesystem generic:
MMCSD_MODE_FAT => MMCSD_MODE_FS
CONFIG_SPL_FAT_LOAD_ARGS_NAME => CONFIG_SPL_FS_LOAD_ARGS_NAME
CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME => CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION => CONFIG_SYS_MMC_SD_FS_BOOT_PARTITION

Signed-off-by: Guillaume GARDET <guillaume.gardet@free.fr>
Cc: Tom Rini <trini@ti.com>
diff --git a/common/spl/spl_fat.c b/common/spl/spl_fat.c
index 56be943..91481fc 100644
--- a/common/spl/spl_fat.c
+++ b/common/spl/spl_fat.c
@@ -106,18 +106,18 @@
 defaults:
 #endif
 
-	err = file_fat_read(CONFIG_SPL_FAT_LOAD_ARGS_NAME,
+	err = file_fat_read(CONFIG_SPL_FS_LOAD_ARGS_NAME,
 			    (void *)CONFIG_SYS_SPL_ARGS_ADDR, 0);
 	if (err <= 0) {
 #ifdef CONFIG_SPL_LIBCOMMON_SUPPORT
 		printf("%s: error reading image %s, err - %d\n",
-		       __func__, CONFIG_SPL_FAT_LOAD_ARGS_NAME, err);
+		       __func__, CONFIG_SPL_FS_LOAD_ARGS_NAME, err);
 #endif
 		return -1;
 	}
 
 	return spl_load_image_fat(block_dev, partition,
-			CONFIG_SPL_FAT_LOAD_KERNEL_NAME);
+			CONFIG_SPL_FS_LOAD_KERNEL_NAME);
 }
 #endif
 #endif