drm/amd/display: remove outdated 8bpc comments

[Why]
The commit c76e483cd9 ("drm/amd/display: Don't restrict bpc to 8 bpc")
removes the historical 8bpc dependency and sets max_bpc to 16.

[How]
The comment that states "8bpc for non-edp" needs to be removed as well.

Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -7244,7 +7244,6 @@ void amdgpu_dm_connector_init_helper(struct amdgpu_display_manager *dm,
 	if (!aconnector->mst_root)
 		drm_connector_attach_max_bpc_property(&aconnector->base, 8, 16);
 
-	/* This defaults to the max in the range, but we want 8bpc for non-edp. */
 	aconnector->base.state->max_bpc = 16;
 	aconnector->base.state->max_requested_bpc = aconnector->base.state->max_bpc;