mxser: spin_lock() => spin_lock_irq()

This should be spin_lock_irq() to match the spin_unlock_irq().  Originally
it was a lock_kernel() but we switched everything to spin_lock_irq() last
November.

[akpm@linux-foundation.org: fix the MOXA_ASPP_MON case too (per Jiri)]
Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/mxser.c

@@ -1768,7 +1768,7 @@ static int mxser_ioctl(struct tty_struct *tty, struct file *file,
 		int len, lsr;
 
 		len = mxser_chars_in_buffer(tty);
-		spin_lock(&info->slock);
+		spin_lock_irq(&info->slock);
 		lsr = inb(info->ioaddr + UART_LSR) & UART_LSR_THRE;
 		spin_unlock_irq(&info->slock);
 		len += (lsr ? 0 : 1);
@@ -1778,12 +1778,12 @@ static int mxser_ioctl(struct tty_struct *tty, struct file *file,
 	case MOXA_ASPP_MON: {
 		int mcr, status;
 
-		spin_lock(&info->slock);
+		spin_lock_irq(&info->slock);
 		status = mxser_get_msr(info->ioaddr, 1, tty->index);
 		mxser_check_modem_status(tty, info, status);
 
 		mcr = inb(info->ioaddr + UART_MCR);
-		spin_unlock(&info->slock);
+		spin_unlock_irq(&info->slock);
 
 		if (mcr & MOXA_MUST_MCR_XON_FLAG)
 			info->mon_data.hold_reason &= ~NPPI_NOTIFY_XOFFHOLD;