ANDROID: KVM: arm64: Don't double account relinquished page

When a page is relinquished by a guest, the pins would be dropped
from pkvm_host_reclaim_page() and it will be unmapped from the guest.
Later, at teardown, if page was unmapped from guest the reclaim
return -ENOENT, in that case we don't need to decrement the pins
again.

Bug: 345727590
Bug: 278749606
Change-Id: Iad07b7689163d6e967d673322bc54a98cb03179a
Signed-off-by: Mostafa Saleh <smostafa@google.com>