sunxi-hdmi: Refactor EDID parsing

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sunxi-hdmi: Add pixelclock override table to edid code

Unfortunately some monitors need pixelclocks which we cannot generate,
often we can workaround this by selecting a pixelclock which is near the
requested pixelclock. This patch adds a table with modes + overriding /
corrected pixelclock, and adds a first entry for the 1680x1050 mode of
Samsung 225bw monitors.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>