ceph: fix warning PTR_ERR_OR_ZERO can be used

change1: fix below warning  reported by coccicheck

/fs/ceph/export.c:371:33-39: WARNING: PTR_ERR_OR_ZERO can be used

change2: typecasted PTR_ERR_OR_ZERO to long as dout expecting long
Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/export.c

@@ -368,7 +368,7 @@ static struct dentry *ceph_get_parent(struct dentry *child)
 	}
 out:
 	dout("get_parent %p ino %llx.%llx err=%ld\n",
-	     child, ceph_vinop(inode), (IS_ERR(dn) ? PTR_ERR(dn) : 0));
+	     child, ceph_vinop(inode), (long)PTR_ERR_OR_ZERO(dn));
 	return dn;
 }