[GPU] Fix shape infer for 0d broadcast (#14744)

src/plugins/intel_gpu/include/intel_gpu/primitives/broadcast.hpp

@@ -107,7 +107,7 @@ struct broadcast : public primitive_base<broadcast> {
           target_shape(target_shape),
           axes_mapping(axes_mapping),
           broadcast_mode(broadcast_spec),
-          broadcast_sizes({}),
+          broadcast_sizes(target_shape.empty() ? tensor(1) : tensor(0)),
           broadcast_axes({}) {}
 
     /// @brief Constructs broadcast primitive / layer with dynamic target_shape.

src/tests/functional/plugin/gpu/shared_tests_instances/single_layer_tests/broadcast.cpp

@@ -25,6 +25,22 @@ const std::vector<InferenceEngine::Precision> inputTPrecisions = {
         InferenceEngine::Precision::BOOL
 };
 
+// NUMPY MODE //////////////////////////////////////////
+// 0D
+std::vector<std::vector<size_t>> targetShapesNumpy0D = {
+        {},
+};
+
+INSTANTIATE_TEST_CASE_P(smoke_TestNumpyBroadcast0D,
+                        BroadcastLayerTest,
+                        ::testing::Combine(::testing::ValuesIn(targetShapesNumpy0D),
+                                           ::testing::Values(ngraph::AxisSet{}),  // not used in numpy mode
+                                           ::testing::Values(ngraph::op::BroadcastType::NUMPY),
+                                           ::testing::Values(std::vector<size_t>{}),
+                                           ::testing::ValuesIn(inputPrecisions),
+                                           ::testing::Values(CommonTestUtils::DEVICE_GPU)),
+                        BroadcastLayerTest::getTestCaseName);
+
 // NUMPY MODE //////////////////////////////////////////
 // 1D
 std::vector<std::vector<size_t>> targetShapesNumpy1D = {