drm/amd/display: Remove unused definition of DMUB SET_CONFIG

[Why & How]
SET_CONFIG transactions with DMUB is not used and removed.
Signed-off-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h

@@ -649,10 +649,6 @@ enum dmub_out_cmd_type {
 	 * Command type used for DP AUX Reply data notification
 	 */
 	DMUB_OUT_CMD__DP_AUX_REPLY = 1,
-	/**
-	 * Command type used for DP HPD event notification
-	 */
-	DMUB_OUT_CMD__DP_HPD_NOTIFY = 2,
 };
 
 #pragma pack(push, 1)