CpuMath Enhancement: Remove any unnecessary Contracts.Assert covered by Span<T> in hardware intrinsics APIs

[briancylui]

Style changes needed to solve part of #823

Details

• In src\Microsoft.ML.CpuMath\CpuMathUtils.netcoreapp.cs, Span<T> might already do the checks (Contracts.Assert) in the public functions. Reference:
  

  machinelearning/src/Microsoft.ML.CpuMath/CpuMathUtils.netcoreapp.cs

  Lines 237 to 245 in e443e2a

  	public static void Scale(float a, float[] dst, int offset, int count)
  	{
  	Contracts.AssertNonEmpty(dst);
  	Contracts.Assert(count > 0);
  	Contracts.Assert(offset >= 0);
  	Contracts.Assert(offset < (dst.Length - count));
  	Scale(a, new Span<float>(dst, offset, count));
  	}