virtio_balloon: Remove redundant __GFP_NOWARN

Commit 16f5dfb ("gfp: include __GFP_NOWARN in GFP_NOWAIT")
made GFP_NOWAIT implicitly include __GFP_NOWARN.

Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT
(e.g., `GFP_NOWAIT | __GFP_NOWARN`) is now redundant. Let's clean
up these redundant flags across subsystems.

No functional changes.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Message-Id: <20250807132643.546237-1-rongqianfeng@vivo.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Author: qianfengrong

drivers/virtio/virtio_balloon.c

@@ -205,7 +205,7 @@ static int virtballoon_free_page_report(struct page_reporting_dev_info *pr_dev_i
 	unsigned int unused, err;
 
 	/* We should always be able to add these buffers to an empty queue. */
-	err = virtqueue_add_inbuf(vq, sg, nents, vb, GFP_NOWAIT | __GFP_NOWARN);
+	err = virtqueue_add_inbuf(vq, sg, nents, vb, GFP_NOWAIT);
 
 	/*
 	 * In the extremely unlikely case that something has occurred and we