Provide correct dpte pointer to indicate absence of dpte

The Pheonix EDD v3.0 spec says that if no dpte is present,
the dpte pointer should contain ffffh:ffffh, not the 0h:0h
which is currently used. This bit me when using NetWare as
a KVM guest.

Signed-off-by: Bruce Rogers <brogers@suse.com>
diff --git a/src/disk.c b/src/disk.c
index 8e1d3ec..0291fe3 100644
--- a/src/disk.c
+++ b/src/disk.c
@@ -615,7 +615,7 @@
         u8 sum = checksum_far(SEG_LOW, &DefaultDPTE, 15);
         SET_LOW(DefaultDPTE.checksum, -sum);
     } else {
-        SET_FARVAR(seg, param_far->dpte.segoff, 0);
+        SET_FARVAR(seg, param_far->dpte.segoff, 0xffffffff);
         bdf = GET_GLOBAL(drive_g->cntl_id);
     }