metal : perform op->type check only once

Author: ggerganov

ggml/src/ggml-metal/ggml-metal.m

@@ -1647,8 +1647,12 @@ static bool ggml_metal_supports_op(const struct ggml_backend_metal_device_contex
     const bool use_bfloat              = ctx_dev->use_bfloat;
 
     if (!use_bfloat) {
+        if (op->type == GGML_TYPE_BF16) {
+            return false;
+        }
+
         for (size_t i = 0, n = 3; i < n; ++i) {
-            if (op->src[i] != NULL && (op->src[i]->type == GGML_TYPE_BF16 || op->type == GGML_TYPE_BF16)) {
+            if (op->src[i] != NULL && op->src[i]->type == GGML_TYPE_BF16) {
                 return false;
             }
         }