env: Rename getenv/_f() to env_get()

We are now using an env_ prefix for environment functions. Rename these
two functions for consistency. Also add function comments in common.h.

Quite a few places use getenv() in a condition context, provoking a
warning from checkpatch. These are fixed up in this patch also.

Suggested-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index 3c887b3..582b685 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -278,7 +278,7 @@
 	  needed in SPL as it has a much simpler task with less
 	  configuration. But some boards use this to support 'Falcon' boot
 	  on EXT2 and FAT, where SPL boots directly into Linux without
-	  starting U-Boot first. Enabling this option will make getenv()
+	  starting U-Boot first. Enabling this option will make env_get()
 	  and env_set() available in SPL.
 
 config SPL_SAVEENV
diff --git a/common/spl/spl_dfu.c b/common/spl/spl_dfu.c
index f5ec0fb..2c97473 100644
--- a/common/spl/spl_dfu.c
+++ b/common/spl/spl_dfu.c
@@ -40,7 +40,7 @@
 
 	/* set default environment */
 	set_default_env(0);
-	str_env = getenv(dfu_alt_info);
+	str_env = env_get(dfu_alt_info);
 	if (!str_env) {
 		error("\"dfu_alt_info\" env variable not defined!\n");
 		return -EINVAL;
diff --git a/common/spl/spl_ext.c b/common/spl/spl_ext.c
index f17c6b9..559ba0b 100644
--- a/common/spl/spl_ext.c
+++ b/common/spl/spl_ext.c
@@ -89,7 +89,7 @@
 		return -1;
 	}
 #if defined(CONFIG_SPL_ENV_SUPPORT)
-	file = getenv("falcon_args_file");
+	file = env_get("falcon_args_file");
 	if (file) {
 		err = ext4fs_open(file, &filelen);
 		if (err < 0) {
@@ -102,7 +102,7 @@
 			       file, err);
 			goto defaults;
 		}
-		file = getenv("falcon_image_file");
+		file = env_get("falcon_image_file");
 		if (file) {
 			err = spl_load_image_ext(spl_image, block_dev,
 						 partition, file);
diff --git a/common/spl/spl_fat.c b/common/spl/spl_fat.c
index 5e31216..60b85f0 100644
--- a/common/spl/spl_fat.c
+++ b/common/spl/spl_fat.c
@@ -113,7 +113,7 @@
 		return err;
 
 #if defined(CONFIG_SPL_ENV_SUPPORT) && defined(CONFIG_SPL_OS_BOOT)
-	file = getenv("falcon_args_file");
+	file = env_get("falcon_args_file");
 	if (file) {
 		err = file_fat_read(file, (void *)CONFIG_SYS_SPL_ARGS_ADDR, 0);
 		if (err <= 0) {
@@ -121,7 +121,7 @@
 			       file, err);
 			goto defaults;
 		}
-		file = getenv("falcon_image_file");
+		file = env_get("falcon_image_file");
 		if (file) {
 			err = spl_load_image_fat(spl_image, block_dev,
 						 partition, file);