drm/msm/dp: fix error return code

Return a negative error code on failure.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
identifier ret; expression e1,e2;
@@
(
if (\(ret < 0\|ret != 0\))
 { ... return ret; }
|
ret = 0
)
... when != ret = e1
    when != &ret
*if(...)
{
  ... when != ret = e2
      when forall
 return ret;
}
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>

drivers/gpu/drm/msm/edp/edp_ctrl.c

@@ -1149,12 +1149,13 @@ int msm_edp_ctrl_init(struct msm_edp *edp)
 	ctrl->aux = msm_edp_aux_init(dev, ctrl->base, &ctrl->drm_aux);
 	if (!ctrl->aux || !ctrl->drm_aux) {
 		pr_err("%s:failed to init aux\n", __func__);
-		return ret;
+		return -ENOMEM;
 	}
 
 	ctrl->phy = msm_edp_phy_init(dev, ctrl->base);
 	if (!ctrl->phy) {
 		pr_err("%s:failed to init phy\n", __func__);
+		ret = -ENOMEM;
 		goto err_destory_aux;
 	}