[mlir][nvgpu] Fix `transposeB` in `nvgpu.warpgroup.mma` (#79271)

The #76150 fixed meaning of `transposeB` in NVVM dialect which was
initially implemented with opposite meaning.

This PR fixes the lowering of `nvgpu.warpgroup.mma` to NVVM dialect.

This will fix two integration tests:
gemm_f32_f16_f16_128x128x128.mlir
gemm_pred_f32_f16_f16_128x128x128.mlir