[New AD] Fix p_norm n=1 issue (#46514)

* fix p_norm n=1 issue

* fix p norm test error

python/paddle/fluid/tests/unittests/autograd/test_orig2prim.py

@@ -462,9 +462,7 @@ class TestPNormOrig2Prim1(TestElementWiseAddOrig2Prim):
         }
 
         self.orig2prim_args = (X, )
-        self.all_ops = [
-            'p_norm', 'reshape_p', 'sqrt_p', 'reduce_sum_p', 'mul_p'
-        ]
+        self.all_ops = ['p_norm', 'reshape_p', 'abs_p', 'reduce_sum_p']
         self.out_map = {0: self.output['Out']}
 
 

python/paddle/incubate/autograd/primrules.py

@@ -344,7 +344,7 @@ def p_norm_orig2prim(op, x):
     if abs(op.attr('porder') - 2.0) < 1e-5:
         return sqrt(reduce_sum(mul(x, x), axis=[0]))
     elif abs(op.attr('porder') - 1.0) < 1e-5:
-        return reduce_sum(sqrt(mul(x, x)), axis=[0])
+        return reduce_sum(primops.abs(x), axis=[0])
     else:
         raise RuntimeError('Only support lower l2/l1 norm currently')