IVGCVSW-1964 : replace optional biases with home-grown Optional

!android-nn-driver:151788

Change-Id: Ibdc41d09b8df05e7a0360dcb8a060860dfb1bd99
diff --git a/src/backends/cl/workloads/ClDepthwiseConvolutionBaseWorkload.cpp b/src/backends/cl/workloads/ClDepthwiseConvolutionBaseWorkload.cpp
index 5a036db..53ac3ba 100644
--- a/src/backends/cl/workloads/ClDepthwiseConvolutionBaseWorkload.cpp
+++ b/src/backends/cl/workloads/ClDepthwiseConvolutionBaseWorkload.cpp
@@ -21,7 +21,7 @@
     const TensorInfo& output,
     const DepthwiseConvolution2dDescriptor& descriptor,
     const TensorInfo& weights,
-    const boost::optional<TensorInfo>& biases)
+    const Optional<TensorInfo>& biases)
 {
     const arm_compute::TensorInfo aclInputInfo = BuildArmComputeTensorInfo(input, descriptor.m_DataLayout);
     const arm_compute::TensorInfo aclOutputInfo = BuildArmComputeTensorInfo(output, descriptor.m_DataLayout);
@@ -32,9 +32,9 @@
 
     if (descriptor.m_BiasEnabled)
     {
-        BOOST_ASSERT(biases.is_initialized());
+        BOOST_ASSERT(biases.has_value());
 
-        aclBiasesInfo = BuildArmComputeTensorInfo(biases.get(), descriptor.m_DataLayout);
+        aclBiasesInfo = BuildArmComputeTensorInfo(biases.value(), descriptor.m_DataLayout);
         optionalAclBiasesInfo = &aclBiasesInfo;
     }