Revert "timer: Added usleep[_range] timer"

This reverts commit 22b8f15c2f7130bb0386f548428df2ffd4e81903 to merge
an advanced version.

Signed-off-by: Thomas Gleixner <[e-mail]>

include/linux/delay.h

···
 void calibrate_delay(void);
 void msleep(unsigned int msecs);
 unsigned long msleep_interruptible(unsigned int msecs);
-void usleep_range(unsigned long min, unsigned long max);
-
-static inline void usleep(unsigned long usecs)
-{
-	usleep_range(usecs, usecs);
-}
 
 static inline void ssleep(unsigned int seconds)
 {

kernel/timer.c

···
 }
 
 EXPORT_SYMBOL(msleep_interruptible);
-
-static int __sched do_usleep_range(unsigned long min, unsigned long max)
-{
-	ktime_t kmin;
-	unsigned long delta;
-
-	kmin = ktime_set(0, min * NSEC_PER_USEC);
-	delta = max - min;
-	return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
-}
-
-/**
- * usleep_range - Drop in replacement for udelay where wakeup is flexible
- * @min: Minimum time in usecs to sleep
- * @max: Maximum time in usecs to sleep
- */
-void usleep_range(unsigned long min, unsigned long max)
-{
-	__set_current_state(TASK_UNINTERRUPTIBLE);
-	do_usleep_range(min, max);
-}
-EXPORT_SYMBOL(usleep_range);