drm/amd/display: Allow PSR exit when panel is disconnected

[HOW&WHY]
Fixed check to only avoid PSR entry when panel
is disconnected. PSR exit can be permitted to restore
the HW to it's non-PSR state.
Reviewed-by: NJayendran Ramani <Jayendran.Ramani@amd.com>
Acked-by: NHamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: NIswara Nagulendran <Iswara.Nagulendran@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -3143,7 +3143,7 @@ bool dc_link_set_psr_allow_active(struct dc_link *link, const bool *allow_active
 	if (!dc_get_edp_link_panel_inst(dc, link, &panel_inst))
 		return false;
 
-	if (allow_active && link->type == dc_connection_none) {
+	if ((allow_active != NULL) && (*allow_active == true) && (link->type == dc_connection_none)) {
 		// Don't enter PSR if panel is not connected
 		return false;
 	}