sandbox: Audit config.h and common.h usage

Remove and replace common.h and config.h in sandbox when it's not needed
and add some explicit includes where needed.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/sandbox/cpu/sdl.c b/arch/sandbox/cpu/sdl.c
index 590e406..ed84646 100644
--- a/arch/sandbox/cpu/sdl.c
+++ b/arch/sandbox/cpu/sdl.c
@@ -72,7 +72,7 @@
 static void sandbox_sdl_poll_events(void)
 {
 	/*
-	 * We don't want to include common.h in this file since it uses
+	 * We don't want to include cpu_func.h in this file since it uses
 	 * system headers. So add a declation here.
 	 */
 	extern void reset_cpu(void);