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/arch/arm/mach-uniphier/board_late_init.c b/arch/arm/mach-uniphier/board_late_init.c
index 4bfa10b..e6d600e 100644
--- a/arch/arm/mach-uniphier/board_late_init.c
+++ b/arch/arm/mach-uniphier/board_late_init.c
@@ -55,7 +55,7 @@
 
 	strncat(dtb_name, ".dtb", buf_len);
 
-	return setenv("fdt_file", dtb_name);
+	return env_set("fdt_file", dtb_name);
 }
 
 int board_late_init(void)
@@ -65,20 +65,20 @@
 	switch (uniphier_boot_device_raw()) {
 	case BOOT_DEVICE_MMC1:
 		printf("eMMC Boot");
-		setenv("bootmode", "emmcboot");
+		env_set("bootmode", "emmcboot");
 		break;
 	case BOOT_DEVICE_NAND:
 		printf("NAND Boot");
-		setenv("bootmode", "nandboot");
+		env_set("bootmode", "nandboot");
 		nand_denali_wp_disable();
 		break;
 	case BOOT_DEVICE_NOR:
 		printf("NOR Boot");
-		setenv("bootmode", "norboot");
+		env_set("bootmode", "norboot");
 		break;
 	case BOOT_DEVICE_USB:
 		printf("USB Boot");
-		setenv("bootmode", "usbboot");
+		env_set("bootmode", "usbboot");
 		break;
 	default:
 		printf("Unknown");