drm/amd/display: Enable eDP ILR on DCN2.1

[WHY]
Enable feature for 21.40
Reviewed-by: Sung Lee <Sung.Lee@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Michael Strauss <michael.strauss@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c

@@ -883,7 +883,8 @@ static const struct dc_debug_options debug_defaults_drv = {
 		.disable_48mhz_pwrdwn = false,
 		.usbc_combo_phy_reset_wa = true,
 		.dmub_command_table = true,
-		.use_max_lb = true
+		.use_max_lb = true,
+		.optimize_edp_link_rate = true
 };
 
 static const struct dc_debug_options debug_defaults_diags = {