ARM: 6747/1: P2V: Thumb2 support

Adding Thumb2 support to the runtime patching of the virt_to_phys and
phys_to_virt opcodes.

Tested both the 8-bit and the 16-bit fixups, using different placements
in memory to exercize all code paths.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Reviewed-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>