pango: re-enable ptest

The run-ptest script got accidently dropped from the SRC_URI during
a past update and ptest patch.

Signed-off-by: Saul Wold <saul.wold@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 4479f810)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>