metal : use mm kernel only for quantum KV cache

Author: ggerganov

ggml-metal.m

@@ -1129,7 +1129,7 @@ void ggml_metal_graph_compute(
                                 !ggml_is_transposed(src1) &&
                                 src1t == GGML_TYPE_F32 &&
                                 ne00 % 32 == 0 && ne00 >= 64 &&
-                                (ne11 > ne11_mm_min || ne12 > 1)) {
+                                (ne11 > ne11_mm_min || (ggml_is_quantized(src0t) && ne12 > 1))) {
                                 //printf("matrix: ne00 = %6d, ne01 = %6d, ne02 = %6d, ne11 = %6d, ne12 = %6d\n", ne00, ne01, ne02, ne11, ne12);
                                 switch (src0->type) {
                                     case GGML_TYPE_F32:  [encoder setComputePipelineState:ctx->pipeline_mul_mm_f32_f32];  break;