[IA64] <asm-ia64/acpi.h> still declares deleted acpi_register_irq.

Signed-off-by: Andreas Schwab <schwab@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>

include/asm-ia64/acpi.h

@@ -96,7 +96,6 @@ static inline void disable_acpi(void) { }
 
 const char *acpi_get_sysname (void);
 int acpi_request_vector (u32 int_type);
-int acpi_register_irq (u32 gsi, u32 polarity, u32 trigger);
 int acpi_gsi_to_irq (u32 gsi, unsigned int *irq);
 
 #ifdef CONFIG_ACPI_NUMA