ARM: enable ARM_PATCH_PHYS_VIRT by default

Enable virtual to physical translation patching by default in all
kernels.  Hide the option behind EMBEDDED.

This can still be turned off if people desire, and they know what
they're doing, to shrink the size of the kernel to a minimum.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>