drm/edid: Make max_tmds_clock kHz instead of MHz

We generally store clocks in kHz, so let's do that for the
HDMI max TMDS clock value as well. Less surpising.

v2: Deal with superfluous code shuffling

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1475070703-6435-4-git-send-email-ville.syrjala@linux.intel.com