virtiofs: remove useless function

Fix the following clang warning:

fs/fuse/virtio_fs.c:130:35: warning: unused function 'vq_to_fpq'
[-Wunused-function].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/virtio_fs.c

@@ -133,11 +133,6 @@ static inline struct virtio_fs_vq *vq_to_fsvq(struct virtqueue *vq)
 	return &fs->vqs[vq->index];
 }
 
-static inline struct fuse_pqueue *vq_to_fpq(struct virtqueue *vq)
-{
-	return &vq_to_fsvq(vq)->fud->pq;
-}
-
 /* Should be called with fsvq->lock held. */
 static inline void inc_in_flight_req(struct virtio_fs_vq *fsvq)
 {