Avoid freeing Vcb when it couldn't have been allocated in UDFPnpSurpriseRemove()

In UDFPnpSurpriseRemove() there is a chance Buf could be not allocated from MyAllocatePool, in such case we should prevent UDFReleaseResource() to release Vcb.
It is just needed to set VcbAcquired = FALSE; and VcbDeleted = FALSE in such case.

CID 1322255