drm/i915/tv: Store the TV oversampling factor in the TV mode

Store the oversampling factor as a number in the TV modes. We
shall want to arithmetic with this which is easier if it's
a number we can use directly.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181112170000.27531-6-ville.syrjala@linux.intel.com


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