fbdev: sh-mobile: HDMI support for SH-Mobile SoCs

Some SH-Mobile SoCs have an HDMI controller and a PHY, attached to one of their
LCDC interfaces. This patch adds a preliminary static support for such
controllers, this means, that only the 720p mode is handled ATM. Support for
more modes and a dynamic switching between them will be added by a follow up
patch.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>