HIP: enable vec fattn on RDNA4 (ggml-org#14323)

Author: IMbackK

ggml/src/ggml-cuda/common.cuh

@@ -241,8 +241,7 @@ static bool fp16_mma_available(const int cc) {
     return false;
 #else
     if ((GGML_CUDA_CC_IS_NVIDIA(cc) && ggml_cuda_highest_compiled_arch(cc) >= GGML_CUDA_CC_VOLTA) ||
-        GGML_CUDA_CC_IS_CDNA(cc) || GGML_CUDA_CC_IS_RDNA3(cc) ||
-        GGML_CUDA_CC_IS_MTHREADS(cc)) {
+        GGML_CUDA_CC_IS_CDNA(cc) || GGML_CUDA_CC_IS_RDNA3(cc)) {
         return true;
     } else if (GGML_CUDA_CC_IS_RDNA4(cc)) {
 #if defined(GGML_HIP_ROCWMMA_FATTN) && defined(GGML_HIP_ROCWMMA_FATTN_GFX12)