KVM: arm64: Correctly populate FAR_EL2 on nested SEA injection

KVM: arm64: Correctly populate FAR_EL2 on nested SEA injection

vcpu_write_sys_reg()'s signature is not totally obvious, and it
is rather easy to write something that looks correct, except that...
Oh wait...

Swap addr and FAR_EL2 to restore some sanity in the nested SEA
department.

Fixes: 9aba641b9ec2a ("KVM: arm64: nv: Respect exception routing rules for SEAs")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250813163747.2591317-1-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>