dmg: Fixing wrong dmg block type value for block terminator.

This is a trivial patch to fix a wrong value for block terminator.
The old value was 0x7fffffff which is wrong. It was not affecting the
code because QEMU dmg block is not handling block terminator right now.
Neverthless, it should be fixed.

Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
Reviewed-by: yuchenlin <yuchenlin@synology.com>
Message-id: 20181228145055.18039-1-jcfaracco@gmail.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block/dmg.c

@@ -54,7 +54,7 @@ enum {
     UDBZ,
     ULFO,
     UDCM = 0x7ffffffe, /* Comments */
-    UDLE               /* Last Entry */
+    UDLE = 0xffffffff  /* Last Entry */
 };
 
 static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)