[NTOS:IO] Do not free the active VPB (#9343)

IopDereferenceVpbAndFree frees a zero-reference VPB only while it is still
installed in RealDevice->Vpb. This can leave the device with a dangling
VPB pointer while detached VPBs are retained.

Reverse the identity test so only a detached, nonpersistent VPB is released
after its reference count reaches zero.

Reference:
- https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/ns-wdm-_vpb

ntoskrnl/io/iomgr/volume.c

@@ -192,7 +192,7 @@ IopDereferenceVpbAndFree(IN PVPB Vpb)
     Vpb->ReferenceCount--;
 
     /* Check if we're out of references */
-    if (!Vpb->ReferenceCount && Vpb->RealDevice->Vpb == Vpb &&
+    if (!Vpb->ReferenceCount && Vpb->RealDevice->Vpb != Vpb &&
         !(Vpb->Flags & VPB_PERSISTENT))
     {
         /* Release VPB lock */