drm/i915: Use intel_hdmi_port_clock() more

Replace the hand rolled intel_hdmi_port_clock() stuff
with the real thing.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210204020846.2094-2-ville.syrjala@linux.intel.com


Reviewed-by: Mika Kahola <mika.kahola@intel.com>