[IA64] fix typo in per_cpu_offset

there is a typo in the definition of per_cpu_offset because, for ia64,
the __per_cpu_offset is an array.
Signed-off-by: Yu Luming <luming.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

include/asm-ia64/percpu.h

@@ -46,7 +46,7 @@
 #ifdef CONFIG_SMP
 
 extern unsigned long __per_cpu_offset[NR_CPUS];
-#define per_cpu_offset(x) (__per_cpu_offset(x))
+#define per_cpu_offset(x) (__per_cpu_offset[x])
 
 /* Equal to __per_cpu_offset[smp_processor_id()], but faster to access: */
 DECLARE_PER_CPU(unsigned long, local_per_cpu_offset);