drm/amd/display: Correctly respond in psr enablement interface

[Why]
dc_link_set_psr_allow_active() always returns true, even in the case
that PSR is not supported.

[How]
Hook up the return value of dc_link_set_psr_allow_active().
Signed-off-by: NCamille Cho <Camille.Cho@amd.com>
Reviewed-by: NJosip Pavic <Josip.Pavic@amd.com>
Acked-by: NAnthony Koo <Anthony.Koo@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link.c

@@ -2557,12 +2557,14 @@ bool dc_link_set_psr_allow_active(struct dc_link *link, bool allow_active, bool
 	struct dmcu *dmcu = dc->res_pool->dmcu;
 	struct dmub_psr *psr = dc->res_pool->psr;
 
+	link->psr_settings.psr_allow_active = allow_active;
+
 	if (psr != NULL && link->psr_settings.psr_feature_enabled)
 		psr->funcs->psr_enable(psr, allow_active);
 	else if ((dmcu != NULL && dmcu->funcs->is_dmcu_initialized(dmcu)) && link->psr_settings.psr_feature_enabled)
 		dmcu->funcs->set_psr_enable(dmcu, allow_active, wait);
-
-	link->psr_settings.psr_allow_active = allow_active;
+	else
+		return false;
 
 	return true;
 }