leds: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.

Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Willy Tarreau <w@1wt.eu>
Cc: linux-leds@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>