libomxil: remove the recipe

Now-removed gstreamer omx plugin was the only consumer, and it's all very obsolete and
hasn't seen development in years.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>