metal : use mm kernels for batch size > 2

Author: ggerganov

ggml-metal.m

@@ -958,7 +958,7 @@ void ggml_metal_graph_compute(
                                 src1t == GGML_TYPE_F32 &&
                                 [ctx->device supportsFamily:MTLGPUFamilyApple7] &&
                                 ne00%32 == 0 &&
-                                ne11 > 1) {
+                                ne11 > 2) {
                                 switch (src0->type) {
                                     case GGML_TYPE_F32:  [encoder setComputePipelineState:ctx->pipeline_mul_mm_f32_f32];  break;
                                     case GGML_TYPE_F16:  [encoder setComputePipelineState:ctx->pipeline_mul_mm_f16_f32];  break;