Currently, arch/arm/mach-uniphier/boot-mode/boot-mode.c is messed up
with unrelated code; there is no reason why the "mmcsetn" command
must be placed in this file.
Split out the MMC code into arch/arm/mach-uniphier/mmc-first-dev.c.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>