irqflags: Explicitly ignore lockdep_hrtimer_exit() argument

When building with 'make W=1' but CONFIG_TRACE_IRQFLAGS=n, the
unused argument to lockdep_hrtimer_exit() causes a warning:

kernel/time/hrtimer.c:1655:14: error: variable 'expires_in_hardirq' set but not used [-Werror=unused-but-set-variable]

This is intentional behavior, so add a cast to void to shut up the warning.

Fixes: 73d2056 ("hrtimer: Don't dereference the hrtimer pointer after the callback")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240408074609.3170807-1-arnd@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202311191229.55QXHVc6-lkp@intel.com/

Author: arndb

include/linux/irqflags.h

@@ -114,7 +114,7 @@ do {						\
 # define lockdep_softirq_enter()		do { } while (0)
 # define lockdep_softirq_exit()			do { } while (0)
 # define lockdep_hrtimer_enter(__hrtimer)	false
-# define lockdep_hrtimer_exit(__context)	do { } while (0)
+# define lockdep_hrtimer_exit(__context)	do { (void)(__context); } while (0)
 # define lockdep_posixtimer_enter()		do { } while (0)
 # define lockdep_posixtimer_exit()		do { } while (0)
 # define lockdep_irq_work_enter(__work)		do { } while (0)