ARM: keystone requires ARM_PATCH_PHYS_VIRT

The dynamic relocation that the keystone platform performs
only works if we can pick the phys offset at boot time. It's
possible that there is another solution for this, but this
is the easiest workaround. Kernels with ARM_PATCH_PHYS_VIRT
are not portable across platforms, and I see no reason why
anyone would run a kernel without ARM_PATCH_PHYS_VIRT on
keystone.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>