ANDROID: KVM: arm64: Fix accounting when VM creation fails

When VM creation fails part-way through __pkvm_create_hyp_vm(), we end
up destroying the partial state by calling __pkvm_destroy_hyp_vm()
before the memory accounting metadata has been updated. Consequently,
we underflow the counters and report wildly incorrect information:

 # cat /sys/kernel/debug/kvm/protected_pgtable_mem
 18446744073709543424

Move the accounting updates immediately after the memcach refill so that
the metadata is in-sync with the donations, even if we fail to create
the VM.

Bug: 278749606
Bug: 373813803
Fixes: 68404834 ("ANDROID: KVM: arm64: Count KVM s2 mmu usage in nVHE protected mode")
Fixes: 590fdd82 ("ANDROID: KVM: arm64: Add memory accounting for the VM pagetable memory")
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: If4ae9816df009ca2a74aff5964676465c25fe6dc