Add small helpers (drm_dp_post_lt_adj_req_supported() and
drm_dp_post_lt_adj_req_in_progress()) to help with implementing
the POST_LT_ADJ_REQ sequence.
Tested-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250718120154.15492-3-ville.syrjala@linux.intel.com