ARM: mach-shmobile: Mackerel VGA camera support

Add VGA camera support to the Mackerel board
using soc_camera_platform.

The VGA camera module is hooked up using the
8-bit CEU bus, and it is constantly bursting
out frames in fixed video mode setting. The
camera module does not allow any I2C control.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>