ARC: clockevent: switch to cpu notifier for clockevent setup

ARC Timers so far have been handled as "legacy" w/o explicit description
in DT. This poses challenge for newer platforms wanting to use them.
This series will eventually help move timers over to DT.

This patch does a small change of using a CPU notifier to set clockevent
on non-boot CPUs. So explicit setup is done only on boot CPU (which will
later be done by DT)

Signed-off-by: Noam Camus <noamc@ezchip.com>
[vgupta: broken off from a bigger patch]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/irq.h

@@ -25,6 +25,5 @@
 #include <asm-generic/irq.h>
 
 extern void arc_init_IRQ(void);
-void arc_local_timer_setup(void);
 
 #endif