sbus-rtc: BKL pushdown

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

drivers/sbus/char/rtc.c

···
  */
 
 #include <linux/module.h>
+#include <linux/smp_lock.h>
 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/miscdevice.h>
···
 {
 	int ret;
 
+	lock_kernel();
 	spin_lock_irq(&mostek_lock);
 	if (rtc_busy) {
 		ret = -EBUSY;
···
 		ret = 0;
 	}
 	spin_unlock_irq(&mostek_lock);
+	unlock_kernel();
 
 	return ret;
 }