Fix the KL algorithm bug when calculated the size of tensor. (#17198)

* resolve #17184

Fix the KL algorithm bug when calculated the size of tensor.

* Add the missing test=develop.

test=develop

python/paddle/fluid/contrib/int8_inference/utility.py

@@ -634,7 +634,8 @@ class Calibrator(object):
                         break
                 starting_iter = int(0.6 * ending_iter)
         bin_width = hist_edeges[1] - hist_edeges[0]
-        P_sum = len(activation_blob)
+
+        P_sum = len(np.array(activation_blob).ravel())
         min_kl_divergence = 0
         min_kl_index = 0
         kl_inited = False