wic: set PARTUUID only for gpt partition table

sgdisk fails to set PARTUUID for msdos partitions as it's only
supported for GPT partitions.

Checked partition table format to run sgdisk --partition-guid
only for GPT partitions.

(From OE-Core rev: 0c1804821917d6d3a062ca19b63667d030138f21)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/utils/partitionedfs.py

@@ -299,7 +299,7 @@ class Image():
                                          (part['num'], part['part_type'],
                                           disk['disk'].device), self.native_sysroot)
 
-            if part['uuid']:
+            if part['uuid'] and disk['ptable_format'] == "gpt":
                 msger.debug("partition %d: set UUID to %s" % \
                             (part['num'], part['uuid']))
                 exec_native_cmd("sgdisk --partition-guid=%d:%s %s" % \