[NTOSKRNL] Properly check for Ft volumes

This fixes a regression introduced in 5ab1cfc which
was causing Unix (BtrFS, ExtX, and so on) volumes not
to be assigned a drive letter assigned anymore. And
thus, they were no longer mounted and presented to the
users.

CORE-16499

ntoskrnl/fstub/disksup.c

@@ -277,7 +277,7 @@ HalpQueryPartitionType(IN PUNICODE_STRING DeviceName,
     }
 
     /* Check if that's a FT volume */
-    if (PartitionInfo.Mbr.PartitionType & PARTITION_NTFT)
+    if (IsFTPartition(PartitionInfo.Mbr.PartitionType))
     {
         *PartitionType = FtPartition;
         return STATUS_SUCCESS;