ARM: keystone: remove redundant depends on ARM_PATCH_PHYS_VIRT

KeyStone is Multi-platform.  ARM_PATCH_PHYS_VIRT is already select'ed
by ARCH_MULTIPLATFORM.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>