[IA64] Use "PER_CPU" form of EXPORT macro

I was gently reminded that there are per-cpu forms of the EXPORT_SYMBOL macros.
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/perfmon.c

@@ -609,7 +609,7 @@ DEFINE_PER_CPU(unsigned long, pfm_syst_info);
 DEFINE_PER_CPU(struct task_struct *, pmu_owner);
 DEFINE_PER_CPU(pfm_context_t  *, pmu_ctx);
 DEFINE_PER_CPU(unsigned long, pmu_activation_number);
-EXPORT_SYMBOL_GPL(per_cpu__pfm_syst_info);
+EXPORT_PER_CPU_SYMBOL_GPL(pfm_syst_info);
 
 
 /* forward declaration */