timers: Expand DEBUG_OBJECTS_TIMER to check if it ever was used

There's been too many bugs happening where a timer is removed, either by
del_timer() or even del_timer_sync() but get's re-armed again by a
workqueue or some other task. Then the timer is freed while it's still
queued to go off. When the timer eventually goes off, as its content no
longer exists, it causes a crash in the timer code.

This is very hard to debug because all evidence of who added the timer is
gone.

Currently, DEBUG_OBJECTS_TIMER will trigger if this happens, but as this
only happens rarely (but in the field, thousands of times) and may depend
on performing various tasks (USB unplug, CPU hotplug, suspend and resume),
not to mention that enabling DEBUG_OBJECTS_TIMER has too much overhead to
run in the field, it seldom catches these types of bugs.

Now that del_timer_shutdown() is to be called before freeing, move the
checks of DEBUG_OBJECTS_TIMER to if it ever gets armed to where
del_timer_shutdown() is called. If there's a case where a timer is armed,
and then freed without calling del_timer_shutdown() DEBUG_OBJECTS_TIMER
will now trigger on it.

This catches cases that are potential issues instead of just catching
when the race condition occurs.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <jstultz@google.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>