As drm_connector already have the display_info, instead of creating
"output_bpc" debugfs in vendor specific driver, move the logic to
the drm layer.

This patch will also move "Current" bpc to the crtc debugfs from
connector debugfs, since we are getting this info from crtc_state.

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220519095149.3560034-4-bhanuprakash.modem@intel.com