[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 <[e-mail]>

arch/ia64/kernel/perfmon.c

···
 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 */