xfree86: Use the TMDS maximum frequency to prune modes

xfree86: Use the TMDS maximum frequency to prune modes

Instead of only relying on the Range section, we can do better on
HDMI to find out what is the max dot clock the monitor supports. The
HDMI CEA vendor block adds a TMDS max freq we can use.

This makes X not prune 4k resolutions on HDMI.

v2: Replace X_INFO by X_PROBED in the message that prints the max
    TMDS frequency (Chris Wilson)

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>