drm/i915/mtl+: Don't enable the AUX_IO power for non-eDP port main links

MTL+ requires the AUX_IO power for the main link only on eDP, so don't
enable it in other cases.

v2:
- Rebased on checking intel_encoder_can_psr() instead of crtc->has_psr.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221114122251.21327-10-imre.deak@intel.com