Revert "tests: gtests: bn: disable int8 tests on gpu"

This reverts commit a04cedb.

tests/gtests/test_batch_normalization_common.hpp

@@ -74,12 +74,6 @@ class bnorm_test_common : public ::testing::TestWithParam<test_bnorm_params_t> {
 
 protected:
     virtual void SetUp() {
-        data_type = data_traits<data_t>::data_type;
-
-        SKIP_IF(data_type == memory::data_type::s8
-                        && get_test_engine_kind() == engine::kind::gpu,
-                "GPU does not support int8 data type.");
-
         p = ::testing::TestWithParam<decltype(p)>::GetParam();
         catch_expected_failures(
                 [=]() { Test(); }, p.expect_to_fail, p.expected_status);
@@ -92,6 +86,7 @@ class bnorm_test_common : public ::testing::TestWithParam<test_bnorm_params_t> {
         eng = get_test_engine();
         strm = make_stream(eng);
 
+        memory::data_type data_type = data_traits<data_t>::data_type;
         ASSERT_TRUE(isF32(data_type) || isS8(data_type));
 
         test_bnorm_sizes_t bs = p.sizes;