request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

Per tglx[1], setup_irq() existed in olden days when allocators were not
ready by the time early interrupts were initialized.

Hence replace setup_irq() by request_irq().

Changing 'ia64_native_register_percpu_irq' decleration to include
'irq_handler_t' as an argument type in arch/ia64/include/asm/hw_irq.h
was causing build error - 'unknown type name 'irq_handler_t''

This was due to below header file sequence,
+ include/interrupt.h
 + include/hardirq.h
  + asm/hardirq.h
   + include/irq.h
    + asm/hw_irq.h
       [ 'ia64_native_register_percpu_irq' declared w/ 'irq_handler_t']
 [ 'irq_handler_t' typedef'ed here in 'include/interrupt.h']

'register_percpu_irq' defined to 'ia64_native_register_percpu_irq' is
the one invoked by the caller, not the latter directly. This was done
to support paravirtualization which was removed around 4 years back.
And 'register_percpu_irq' is invoked only inside 'arch/ia64/kernel'.

So 'register_percpu_irq' define to 'ia64_native_register_percpu_irq' is
removed, instead 'ia64_native_register_percpu_irq' is renamed to
'register_precpu_irq()' & it is directly invoked. Also,
'register_precpu_irq()' is declared in a new header file 'irq.h' inside
'arch/ia64/kernel/', this header file is included by C files invoking
'register_percpu_irq()'.

[1] https://lkml.kernel.org/r/alpine.DEB.2.20.1710191609480.1971@nanosSigned-off-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>