ARM: UniPhier: consolidate board_postclk_init() function
This commit merges
arch/arm/cpu/armv7/uniphier/ph1-*/board_postclk_init.c
to
arch/arm/cpu/armv7/uniphier/board_postclk_init.c
Because PH1-Pro4 does not have the BCU block, add __weak to
bcu_init().
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>