mx2_camera: Add soc_camera support for i.MX25/i.MX27

This is the soc_camera support developed by Sascha Hauer for the i.MX27.  Alan
Carvalho de Assis modified the original driver to get it working on more recent
kernels. I modified it further to add support for i.MX25. This driver has been
tested on i.MX25 and i.MX27 based platforms.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>