riscv: Remove common.h usage

We can remove common.h from most cases of the code here, and only a few
places need an additional header instead.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Rick Chen <rick@andestech.com>

arch/riscv/lib/spl.c

@@ -3,7 +3,6 @@
  * Copyright (C) 2019 Fraunhofer AISEC,
  * Lukas Auer <lukas.auer@aisec.fraunhofer.de>
  */
-#include <common.h>
 #include <cpu_func.h>
 #include <hang.h>
 #include <init.h>