env: Rename setenv() to env_set()

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

Suggested-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/logicpd/imx6/imx6logic.c b/board/logicpd/imx6/imx6logic.c
index 0a7d412..78fc546 100644
--- a/board/logicpd/imx6/imx6logic.c
+++ b/board/logicpd/imx6/imx6logic.c
@@ -173,11 +173,11 @@
 
 int board_late_init(void)
 {
-	setenv("board_name", "imx6logic");
+	env_set("board_name", "imx6logic");
 
 	if (is_mx6dq()) {
-		setenv("board_rev", "MX6DQ");
-		setenv("fdt_file", "imx6q-logicpd.dtb");
+		env_set("board_rev", "MX6DQ");
+		env_set("fdt_file", "imx6q-logicpd.dtb");
 	}
 
 	return 0;
diff --git a/board/logicpd/omap3som/omap3logic.c b/board/logicpd/omap3som/omap3logic.c
index f8b9f68..e86e0c3 100644
--- a/board/logicpd/omap3som/omap3logic.c
+++ b/board/logicpd/omap3som/omap3logic.c
@@ -220,7 +220,7 @@
 
 		/* If the user has not set fdtimage, set the default */
 		if (!getenv("fdtimage"))
-			setenv("fdtimage", board->fdtfile);
+			env_set("fdtimage", board->fdtfile);
 	}
 
 	/* restore hsusb0_data5 pin as hsusb0_data5 */