staging: most: net: use DEFINE_MUTEX() for mutex lock

mutex lock can be initialized automatically with DEFINE_MUTEX()
rather than explicitly calling mutex_init().
Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com>
Link: https://lore.kernel.org/r/20201224132519.31504-1-zhengyongjun3@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/net/net.c

@@ -68,7 +68,7 @@ struct net_dev_context {
 };
 
 static struct list_head net_devices = LIST_HEAD_INIT(net_devices);
-static struct mutex probe_disc_mt; /* ch->linked = true, most_nd_open */
+static DEFINE_MUTEX(probe_disc_mt); /* ch->linked = true, most_nd_open */
 static DEFINE_SPINLOCK(list_lock); /* list_head, ch->linked = false, dev_hold */
 static struct most_component comp;
 
@@ -520,7 +520,6 @@ static int __init most_net_init(void)
 {
 	int err;
 
-	mutex_init(&probe_disc_mt);
 	err = most_register_component(&comp);
 	if (err)
 		return err;