xenbus: drop useless LIST_HEAD in xenbus_write_watch() and xenbus_file_write()

Drop LIST_HEAD where the variable it declares is never used.

The declarations were introduced with the file, but the declared
variables were not used.

Fixes: 1107ba88 ("xen: add xenfs to allow usermode <-> Xen interaction")
Signed-off-by: NMao Wenan <maowenan@huawei.com>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>

drivers/xen/xenbus/xenbus_dev_frontend.c

@@ -465,7 +465,6 @@ static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u)
 	struct watch_adapter *watch;
 	char *path, *token;
 	int err, rc;
-	LIST_HEAD(staging_q);
 
 	path = u->u.buffer + sizeof(u->u.msg);
 	token = memchr(path, 0, u->u.msg.len);
@@ -523,7 +522,6 @@ static ssize_t xenbus_file_write(struct file *filp,
 	uint32_t msg_type;
 	int rc = len;
 	int ret;
-	LIST_HEAD(staging_q);
 
 	/*
 	 * We're expecting usermode to be writing properly formed