vhost: Make parameter name match of vhost_get_vq_desc()

The parameter name in the function declaration and definition
should be the same.

drivers/vhost/vhost.h,
int vhost_get_vq_desc(..., unsigned int iov_count,...);

drivers/vhost/vhost.c,
int vhost_get_vq_desc(..., unsigned int iov_size,...)
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
Message-Id: <20230621093835.36878-1-xianting.tian@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/vhost.h

@@ -200,7 +200,7 @@ bool vhost_log_access_ok(struct vhost_dev *);
 void vhost_clear_msg(struct vhost_dev *dev);
 
 int vhost_get_vq_desc(struct vhost_virtqueue *,
-		      struct iovec iov[], unsigned int iov_count,
+		      struct iovec iov[], unsigned int iov_size,
 		      unsigned int *out_num, unsigned int *in_num,
 		      struct vhost_log *log, unsigned int *log_num);
 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);