arm64: kvm: eliminate literal pool entries

Replace two instances of 'ldr xN, =(constant)' in the world switch
hot path with 'mov' instructions.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>