ARM64: KVM: store kvm_vcpu_fault_info est_el2 as word

esr_el2 field of struct kvm_vcpu_fault_info has u32 type.
It should be stored as word. Current code works in LE case
because existing puts least significant word of x1 into
esr_el2, and it puts most significant work of x1 into next
field, which accidentally is OK because it is updated again
by next instruction. But existing code breaks in BE case.

Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>