Fix issues on Windows for Vitis AI (#15810)
### Description
Fix two errors that is only encountered on windows
### Motivation and Context
For onnxruntime::VitisAIProviderFactoryCreator::Create, it would cause
the compile error.
For if (it == provider_options_map.end()), it would cause an error but
execute as normal
Co-authored-by: Zhang <yueqingz@amd.com>
