Performance improvement to MLOpenConvDirUniC kernel
Performance improvement to MLOpenConvDirUniC kernel

1. Avoid FP division by 1.
2. Simplify arithmetic if divisor is a power of two
3. Use uniform wave_id with LC
4. Placed __restrict modifier on pointer arguments.
5. Changed from int to uint types. This really better represents the range used,
   while allows compiler to omit overflow checks.

ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen