mark FA with sinks as unsupported for now

Author: rmatif

ggml/src/ggml-opencl/ggml-opencl.cpp

@@ -2631,6 +2631,10 @@ static bool ggml_opencl_supports_op(ggml_backend_dev_t dev, const struct ggml_te
             return op->src[0]->type == GGML_TYPE_F32 && ggml_is_contiguous(op->src[0]);
         case GGML_OP_FLASH_ATTN_EXT:
             {
+                if (op->src[4]) {
+                    return false;
+                }
+
                 const ggml_tensor * q = op->src[0];
                 const ggml_tensor * k = op->src[1];
                 const ggml_tensor * v = op->src[2];