[IA64] cleanup dig_irq_init

dig_irq_init is equivalent to machvec_noop, no need to define
another empty function.
Signed-off-by: NKen Chen <kenneth.w.chen@intel.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

arch/ia64/dig/setup.c

@@ -69,8 +69,3 @@ dig_setup (char **cmdline_p)
 	screen_info.orig_video_isVGA = 1;	/* XXX fake */
 	screen_info.orig_video_ega_bx = 3;	/* XXX fake */
 }
-
-void __init
-dig_irq_init (void)
-{
-}

include/asm-ia64/machvec_dig.h

@@ -2,7 +2,6 @@
 #define _ASM_IA64_MACHVEC_DIG_h
 
 extern ia64_mv_setup_t dig_setup;
-extern ia64_mv_irq_init_t dig_irq_init;
 
 /*
  * This stuff has dual use!
@@ -13,6 +12,5 @@ extern ia64_mv_irq_init_t dig_irq_init;
  */
 #define platform_name		"dig"
 #define platform_setup		dig_setup
-#define platform_irq_init	dig_irq_init
 
 #endif /* _ASM_IA64_MACHVEC_DIG_h */