fbdev: sh_mobile_hdmi: add support for E-EDID parsing

Many HDMI clients implement enhanced EDID blocks, which often contain
additional supported video modes. This patch implements parsing of such
E-EDID blocks.

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