KVM: arm64: Return early from kvm_finalize_sys_regs() if guest has run

KVM: arm64: Return early from kvm_finalize_sys_regs() if guest has run

If the guest has already run, we have no business finalizing the
system register state - it is too late. Therefore, check early and
bail if the VM has already run.

This change also stops kvm_init_nv_sysregs() from being called once
the RM has run once. Although this looks like a behavioural change,
the function returns early once it has been called the first time.

Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Link: https://patch.msgid.link/20260319154937.3619520-4-sascha.bischoff@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>