ARM64: KVM: MMIO support BE host running LE code

ARM64: KVM: MMIO support BE host running LE code

In case of guest CPU running in LE mode and host runs in
BE mode we need byteswap data, so read/write is emulated correctly.

Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
(cherry picked from commit b30070862edbdb252f9d0d3a1e61b8dc4c68e3d2)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>