arm64: KVM: move HCR_EL2.{IMO,FMO} manipulation into the vgic switch code

arm64: KVM: move HCR_EL2.{IMO,FMO} manipulation into the vgic switch code

GICv3 requires the IMO and FMO bits to be tightly coupled with some
of the interrupt controller's register switch.

In order to have similar code paths, move the manipulation of these
bits to the GICv2 switch code.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
(cherry picked from commit ac3c3747e2db2f326ffc601651de544cdd33a8e9)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>