drm/i915: move intel_display_device_probe() one level higher

Don't hide display probe in device info code.

Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230912120537.2158209-3-jani.nikula@intel.com