MKLDNN elementwise_mul: Revert changes to eltwise_add tests

Author: Sand3r-

python/paddle/fluid/tests/unittests/test_elementwise_add_op.py

@@ -43,13 +43,19 @@ def test_check_output(self):
         self.check_output()
 
     def test_check_grad_normal(self):
+        if self.dtype == np.float16:
+            return
         self.check_grad(['X', 'Y'], 'Out', max_relative_error=0.005)
 
     def test_check_grad_ingore_x(self):
+        if self.dtype == np.float16:
+            return
         self.check_grad(
             ['Y'], 'Out', max_relative_error=0.005, no_grad_set=set("X"))
 
     def test_check_grad_ingore_y(self):
+        if self.dtype == np.float16:
+            return
         self.check_grad(
             ['X'], 'Out', max_relative_error=0.005, no_grad_set=set('Y'))