video: meson: Add fallback to default timings for QHD/UHD monitors

video: meson: Add fallback to default timings for QHD/UHD monitors

The HDMI driver currently supports only up to 1920x1200 resolutions
and QHD/UHD monitors might not specify detailed timings in EDID other
than those for their maximum resolution, even though they work with
lower resolutions like full HD. In such cases display_read_timings()
will fail breaking the video output driver initialization.

As a workaround fallback to full HD timings is added for QHD or UHD
monitors. The default timing will only be used when "hdmimode"
environment variable is set to "1080p60hz", otherwise the driver
switches to CVBS mode as before, when display timings are
unsupported/could not be read.

The proper solution would be to implement support for 2K/4K HDMI
modes, which are also not supported yet by driver in the kernel.

Change-Id: I407228392a6b1b6e8b0c55a6962235111df0c69c
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>