drm/i915: Move HDMI vswing programming to the right place

The documented programming sequence indicates the correct point
for the vswing programming is just before we enable the DDI.
Make it so.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210128155948.13678-4-ville.syrjala@linux.intel.com


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