tty: n_gsm: use DEFINE_SPINLOCK() for spinlock

spinlock can be initialized automatically with DEFINE_SPINLOCK()
rather than explicitly calling spin_lock_init().
Reported-by: Hulk Robot <hulkci@huawei.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Guobin Huang <huangguobin4@huawei.com>
Link: https://lore.kernel.org/r/1617710163-48158-1-git-send-email-huangguobin4@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/n_gsm.c

@@ -266,7 +266,7 @@ struct gsm_mux {
 
 #define MAX_MUX		4			/* 256 minors */
 static struct gsm_mux *gsm_mux[MAX_MUX];	/* GSM muxes */
-static spinlock_t gsm_mux_lock;
+static DEFINE_SPINLOCK(gsm_mux_lock);
 
 static struct tty_driver *gsm_tty_driver;
 
@@ -3257,8 +3257,6 @@ static int __init gsm_init(void)
 	gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
 	tty_set_operations(gsm_tty_driver, &gsmtty_ops);
 
-	spin_lock_init(&gsm_mux_lock);
-
 	if (tty_register_driver(gsm_tty_driver)) {
 		put_tty_driver(gsm_tty_driver);
 		tty_unregister_ldisc(N_GSM0710);