drm/amd/powerplay: avoid NULL dereference, cz_hwmgr.c

if (a == NULL || a->b == NULL)
leads to a NULL pointer dereference if a == NULL.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/hwmgr/cz_hwmgr.c

@@ -1218,7 +1218,7 @@ static int cz_hwmgr_backend_init(struct pp_hwmgr *hwmgr)
 
 static int cz_hwmgr_backend_fini(struct pp_hwmgr *hwmgr)
 {
-	if (hwmgr != NULL || hwmgr->backend != NULL) {
+	if (hwmgr != NULL && hwmgr->backend != NULL) {
 		kfree(hwmgr->backend);
 		kfree(hwmgr);
 	}