ARM: KVM: Fix kvm_set_pte assignment

THe kvm_set_pte function was actually assigning the entire struct to the
structure member, which should work because the structure only has that
one member, but it is still not very nice.

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