MIPS: Reduce kernel image size for !CONFIG_DEBUG_ZBOOT

!CONFIG_DEBUG_ZBOOT doesn't need puts() and puthex(), remove them and
the corrospindig strings for !CONFIG_DEBUG_ZBOOT, as a result, it saves
about 1280 bytes.

[ralf@linux-mips.org: Resolved reject.]

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/1898/


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