drm/i915/dp: Ensure panel power remains enabled during connector detection

drm/i915/dp: Ensure panel power remains enabled during connector detection

The sink's capabilities, like the DSC caps, depend on the source OUI
written to the sink's DPCD registers and so this OUI value should be
valid for the whole duration of the detection. An eDP sink will reset
this OUI value when the panel power is disabled, so prevent the
disabling - happening by default after a 1 sec idle period - for the
whole duration of detection.

v2: Update the documentation for intel_pps_on(). (Jani)

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241025160259.3088727-3-imre.deak@intel.com