SQUEEZE operator's input #1 can be nullptr.

When num_squeeze_dims is zero the data pointer should be nullptr.

This addresses the following error when running NNAPIDelegate.SqueezeSimpleTest:
ANeuralNetworksModel_setOperandValue setting operand 1 which has operand type that is not fully specified

PiperOrigin-RevId: 235772184

tensorflow/lite/delegates/nnapi/nnapi_delegate.cc

@@ -648,7 +648,7 @@ class NNAPIDelegateKernel {
             // Note that we add the squeeze dimensions even if the dimensions
             // were unspecified (empty), as NNAPI requires the operand.
             mapping_args.builder->AddVectorInt32Operand(
-                builtin->squeeze_dims,
+                builtin->num_squeeze_dims ? builtin->squeeze_dims : nullptr,
                 static_cast<uint32_t>(builtin->num_squeeze_dims));
             return ANEURALNETWORKS_SQUEEZE;
           };