drm/i915/ptl: Use everywhere the correct DDI port clock select mask

drm/i915/ptl: Use everywhere the correct DDI port clock select mask

The PTL XELPDP_PORT_CLOCK_CTL register XELPDP_DDI_CLOCK_SELECT field's
size is 5 bits vs. the earlier platforms where its size is 4 bits. Make
sure the field is read-out/programmed everywhere correctly, according to
the above.

Cc: Mika Kahola <mika.kahola@intel.com>
Cc: stable@vger.kernel.org # v6.13+
Tested-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250512142600.824347-1-imre.deak@intel.com