[media] soc-camera/sh_mobile_csi2: remove unused driver

The sh_mobile_csi2 isn't used anymore (was it ever?), so remove it.
Especially since the soc-camera framework is being deprecated.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>