ARM: uniphier: remove unneeded header inclusion from board_late_init.c

<nand.h> is unneeded since commit 9248a78f ("ARM: UniPhier: remove
Denali NAND controller fixup code").

<linux/io.h> is uneeded since commit 1320fa2e ("ARM: uniphier:
remove workaround for the NAND write protect").

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>