Convert the bindings of the Freescale Pixel Pipeline to YAML.

The conversion drops the previously listed compatibles for several SoCs.
It is unclear, if the PXP on these SoCs is compatible to any of the PXPs
on the existing SoCs and would allow to reuse the already defined
compatibles. The missing compatibles should be brought back when the
support for the PXP on these SoCs is added.
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>