kmod: remove unused ptest.patch

* it was removed from SRC_URI in 2015:
  https://git.openembedded.org/openembedded-core/commit/?id=f80d136bdd578468035a88125fa1b84973fd912b



Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit cfc4586b)
Signed-off-by: Steve Sakoman <steve@sakoman.com>