ACPI: IA64=y ACPI=n build fix

ia64's sim_defconfig uses CONFIG_ACPI=n
which now #define's acpi_disabled in <linux/acpi.h>

So we shouldn't re-define it here in <asm/acpi.h>
Signed-off-by: Len Brown <len.brown@intel.com>

arch/ia64/include/asm/acpi.h

@@ -89,10 +89,12 @@ ia64_acpi_release_global_lock (unsigned int *lock)
 #define ACPI_RELEASE_GLOBAL_LOCK(facs, Acq)				\
 	((Acq) = ia64_acpi_release_global_lock(&facs->global_lock))
 
+#ifdef	CONFIG_ACPI
 #define acpi_disabled 0	/* ACPI always enabled on IA64 */
 #define acpi_noirq 0	/* ACPI always enabled on IA64 */
 #define acpi_pci_disabled 0 /* ACPI PCI always enabled on IA64 */
 #define acpi_strict 1	/* no ACPI spec workarounds on IA64 */
+#endif
 #define acpi_processor_cstate_check(x) (x) /* no idle limits on IA64 :) */
 static inline void disable_acpi(void) { }