sh: add Video Output Unit (VOU) and AK8813 TV-encoder support to ms7724se

Add platform bindings, GPIO initialisation and allocation and AK8813 reset code
to ms7724se.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>