drm/i915/tv: Add 1080p30/50/60 TV modes

Add the missing 1080p TV modes. On gen4 all of them work just fine,
whereas on gen3 only the 30Hz mode actually works correctly.

v2: s/IS_GEN3(dev_priv)/IS_GEN(dev_priv, 3)/

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181112170000.27531-14-ville.syrjala@linux.intel.com


Reviewed-by: Imre Deak <imre.deak@intel.com>