virtio_ring: Fix kernel-doc

Fix function name in virtio_ring.c kernel-doc comment
to remove a warning found by clang_w1.

drivers/virtio/virtio_ring.c:1903: warning: expecting prototype for
virtqueue_get_buf(). Prototype was for virtqueue_get_buf_ctx() instead
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/1621998731-17445-1-git-send-email-yang.lee@linux.alibaba.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_ring.c

@@ -1875,7 +1875,7 @@ bool virtqueue_kick(struct virtqueue *vq)
 EXPORT_SYMBOL_GPL(virtqueue_kick);
 
 /**
- * virtqueue_get_buf - get the next used buffer
+ * virtqueue_get_buf_ctx - get the next used buffer
  * @_vq: the struct virtqueue we're talking about.
  * @len: the length written into the buffer
  * @ctx: extra context for the token