[IA64] fix section mismatch in arch/ia64/kernel/acpi.c

This patch kills:

	WARNING: vmlinux.o(.text+0x1702): Section mismatch in
	reference from the function acpi_register_ioapic() to the
	function .devinit.text:iosapic_init()

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index c7467f8..19709a0 100644
--- a/arch/ia64/kernel/acpi.c
+++ b/arch/ia64/kernel/acpi.c
@@ -966,7 +966,7 @@
 fs_initcall(acpi_map_iosapics);
 #endif				/* CONFIG_ACPI_NUMA */
 
-int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base)
+int __ref acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base)
 {
 	int err;