tlclk: remove big kernel lock

This driver already has a global mutex, so let's just
use that in the open function instead of the BKL.
It may not even be needed there, but this patch should
have the smallest impact.

Signed-off-by: Arnd Bergmann <[e-mail]>
Cc: Mark Gross <[e-mail]>

drivers/char/tlclk.c

···
 #include <linux/ioport.h>
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/timer.h>
 #include <linux/sysfs.h>
 #include <linux/device.h>
···
 {
 	int result;
 
-	lock_kernel();
+	mutex_lock(&tlclk_mutex);
 	if (test_and_set_bit(0, &useflags)) {
 		result = -EBUSY;
 		/* this legacy device is always one per system and it doesn't
···
 		inb(TLCLK_REG6);	/* Clear interrupt events */
 
 out:
-	unlock_kernel();
+	mutex_unlock(&tlclk_mutex);
 	return result;
 }