Revert "Create grouped_mm for bf16 and fp16 inputs on Blackwell (#5101)"

This reverts commit 515a337.

Author: wujingyue

CMakeLists.txt

@@ -135,7 +135,6 @@ if(BUILD_CUTLASS)
 
     set(NVFUSER_CUTLASS_SRCS)
     list(APPEND NVFUSER_CUTLASS_SRCS
-        ${NVFUSER_CUTLASS}/group_mm.cu
         ${NVFUSER_CUTLASS}/nvfp4_scaled_mm.cu
         ${NVFUSER_CUTLASS}/nvfp4_scaled_mm_blockscale.cu
         ${NVFUSER_CUTLASS}/nvfp4_scaled_group_mm.cu