ARC: opencode arc_request_percpu_irq

- The idea is to remove the API usage since it has a subltle
  design flaw - relies on being called on cpu0 first. This is true for
  some early per cpu irqs such as TIMER/IPI, but not for late probed
  per cpu peripherals such a perf. And it's usage in perf has already
  bitten us once: see c6317bc7c5
  ("ARCv2: perf: Ensure perf intr gets enabled on all cores") where we
  ended up open coding it anyways

- The seeming duplication will go away once we start using cpu notifier
  for timer setup

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/irq.h

@@ -26,8 +26,5 @@
 
 extern void arc_init_IRQ(void);
 void arc_local_timer_setup(void);
-void arc_request_percpu_irq(int irq, int cpu,
-                            irqreturn_t (*isr)(int irq, void *dev),
-                            const char *irq_nm, void *percpu_dev);
 
 #endif