ARM: OMAP: Fix warning in timer32k.c if CONFIG_NO_IDLE_HZ
isn't set:

arch/arm/plat-omap/timer32k.c:221: warning:
'omap_32k_timer_handler' defined but not used

Signed-off-by: Dirk Behme <dirk.behme_at_gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>