[D3D12] - Correct ShaderModel and rename to CheckShaderModel. [D3D12] - Add new CheckMaxSupportedFeatureLevel
[D3D12] - Correct ShaderModel and rename to CheckShaderModel.
[D3D12] - Add new CheckMaxSupportedFeatureLevel

sharpdx/SharpDX,sharpdx/SharpDX,sharpdx/SharpDX