ANDROID: KVM: arm64: Don't copy pvmfw pages more than once

If a pvmfw page is relinquished from the guest back to the host, disable
subsequent re-faulting of the pvmfw image for the pVM if a new page is
donated back to the same IPA region.

Bug: 432439762
Change-Id: Ibe7ba22bc19cad0a7c31dedae64c29e10537b669
Signed-off-by: Sebastian Ene <sebastianene@google.com>