arg : add --no-mmproj-offload (#13093)

* arg : add --no-mmproj-offload

* Update common/arg.cpp

common/common.h

@@ -342,6 +342,7 @@ struct common_params {
 
     // multimodal models (see examples/llava)
     struct common_params_model mmproj;
+    bool mmproj_use_gpu = true;     // use GPU for multimodal model
     bool no_mmproj = false;         // explicitly disable multimodal model
     std::vector<std::string> image; // path to image file(s)