buildhistory-diff: honour report_all flag

Make sure that we're passing a bool value. Without this, buildhistory
shows all the output for all the keys/fields when it shouldn't be by
default.

(From OE-Core rev: b30153a15715a83c0f9a7d7d1883a15404992a19)

Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/buildhistory-diff

@@ -38,7 +38,7 @@ def get_args_parser():
     parser.add_argument('-a', '--report-all',
                         action='store_true',
                         dest='report_all',
-                        default='False',
+                        default=False,
                         help="Report all changes, not just the default significant ones")
     parser.add_argument('-s', '---signatures',
                         action='store_true',