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/drivers/video/ati_radeon_fb.c b/drivers/video/ati_radeon_fb.c
index 07a29ea..5b6c422 100644
--- a/drivers/video/ati_radeon_fb.c
+++ b/drivers/video/ati_radeon_fb.c
@@ -637,7 +637,8 @@
 
 	videomode = CONFIG_SYS_DEFAULT_VIDEO_MODE;
 	/* get video mode via environment */
-	if ((penv = getenv ("videomode")) != NULL) {
+	penv = env_get("videomode");
+	if (penv) {
 		/* deceide if it is a string */
 		if (penv[0] <= '9') {
 			videomode = (int) simple_strtoul (penv, NULL, 16);
diff --git a/drivers/video/cfb_console.c b/drivers/video/cfb_console.c
index b6fc7e1..6c5425c 100644
--- a/drivers/video/cfb_console.c
+++ b/drivers/video/cfb_console.c
@@ -1856,7 +1856,7 @@
 	splash_get_pos(&video_logo_xpos, &video_logo_ypos);
 
 #ifdef CONFIG_SPLASH_SCREEN
-	s = getenv("splashimage");
+	s = env_get("splashimage");
 	if (s != NULL) {
 		ret = splash_screen_prepare();
 		if (ret < 0)
diff --git a/drivers/video/mb862xx.c b/drivers/video/mb862xx.c
index 1c74e97..e0565e1 100644
--- a/drivers/video/mb862xx.c
+++ b/drivers/video/mb862xx.c
@@ -246,7 +246,8 @@
 	tmp = 0;
 	videomode = 0x310;
 	/* get video mode via environment */
-	if ((penv = getenv ("videomode")) != NULL) {
+	penv = env_get("videomode");
+	if (penv) {
 		/* decide if it is a string */
 		if (penv[0] <= '9') {
 			videomode = (int) simple_strtoul (penv, NULL, 16);
diff --git a/drivers/video/mx3fb.c b/drivers/video/mx3fb.c
index 51d06d6..78e595e 100644
--- a/drivers/video/mx3fb.c
+++ b/drivers/video/mx3fb.c
@@ -816,7 +816,7 @@
 
 	videomode = CONFIG_SYS_DEFAULT_VIDEO_MODE;
 	/* get video mode via environment */
-	penv = getenv("videomode");
+	penv = env_get("videomode");
 	if (penv) {
 		/* decide if it is a string */
 		if (penv[0] <= '9') {
diff --git a/drivers/video/mxsfb.c b/drivers/video/mxsfb.c
index 0ddce3d..9d810ba 100644
--- a/drivers/video/mxsfb.c
+++ b/drivers/video/mxsfb.c
@@ -161,7 +161,7 @@
 	puts("Video: ");
 
 	/* Suck display configuration from "videomode" variable */
-	penv = getenv("videomode");
+	penv = env_get("videomode");
 	if (!penv) {
 		puts("MXSFB: 'videomode' variable not set!\n");
 		return NULL;
diff --git a/drivers/video/videomodes.c b/drivers/video/videomodes.c
index cf71ad1..6d96b33 100644
--- a/drivers/video/videomodes.c
+++ b/drivers/video/videomodes.c
@@ -165,7 +165,8 @@
 	/* first search for the environment containing the real param string */
 	s = penv;
 
-	if ((p = getenv (s)) != NULL)
+	p = env_get(s);
+	if (p)
 		s = p;
 
 	/*
@@ -234,7 +235,7 @@
 int video_get_video_mode(unsigned int *xres, unsigned int *yres,
 	unsigned int *depth, unsigned int *freq, const char **options)
 {
-	char *p = getenv("video-mode");
+	char *p = env_get("video-mode");
 	if (!p)
 		return 0;