ARM: uniphier: drop #include <init.h> again from umc-pxs2.c

I do not understand the change made to this file by
commit 691d719d ("common: Drop init.h from common header").

  git show 691d719d -- arch/arm/mach-uniphier/dram/umc-pxs2.c

This file does not call or define any functions declared in <init.h>

Simply revert the change made to this file.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>