MIPS: Quiet the building output of vmlinux.32 and vmlinux.64

Based on quiet_cmd_X and cmd_X, this patch quiets the building output of
vmlinux.32 and vmlinux.64.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: Sam Ravnborg <sam@ravnborg.org>
Patchwork: https://patchwork.linux-mips.org/patch/1766/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>