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/include/dataflash.h b/include/dataflash.h
index 84a56c3..c9f2220 100644
--- a/include/dataflash.h
+++ b/include/dataflash.h
@@ -197,7 +197,7 @@
 
 extern void dataflash_print_info (void);
 extern void dataflash_perror (int err);
-extern void AT91F_DataflashSetEnv (void);
+extern void AT91F_Dataflashenv_set(void);
 
 extern struct dataflash_addr cs[CONFIG_SYS_MAX_DATAFLASH_BANKS];
 extern dataflash_protect_t area_list[NB_DATAFLASH_AREA];