sh: fix MSIOF0 SPI on ecovec: it conflicts with VOU

MSIOF0 and VOU share pins on sh7724, make MSIOF0 available again, as long as
VOU is not configured.

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