ia64 idle: delete stale (*idle)() function pointer

Commit 3e7fc708eb ("ia64 idle: delete pm_idle") in 3.9-rc1 didn't
finish the job, leaving an un-initialized reference to (*idle)().

[ Haven't seen a crash from this - but seems like we are just being
  lucky that "idle" is zero so it does get initialized before we jump to
  randomland  - Len ]

Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/ia64/kernel/process.c

@@ -291,7 +291,6 @@ cpu_idle (void)
 		}
 
 		if (!need_resched()) {
-			void (*idle)(void);
 #ifdef CONFIG_SMP
 			min_xtp();
 #endif
@@ -299,9 +298,7 @@ cpu_idle (void)
 			if (mark_idle)
 				(*mark_idle)(1);
 
-			if (!idle)
-				idle = default_idle;
-			(*idle)();
+			default_idle();
 			if (mark_idle)
 				(*mark_idle)(0);
 #ifdef CONFIG_SMP