ACPI: fix early DSDT dmi check warnings on ia64

WARNING: at drivers/firmware/dmi_scan.c:423 dmi_matches+0x70/0x160()
dmi check: not initialized yet.

This is caused by commit aa2110c
(ACPI: add boot option acpi=copy_dsdt to fix corrupt DSDT).
DMI is not initialized yet in acpi_early_init on ia64.

The DSDT DMI check table is x86 specific, so make it empty on other archs.
And this fixes the warnings on ia64.

Reported-and-tested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/bus.c

@@ -69,6 +69,7 @@ static struct dmi_system_id __cpuinitdata power_nocheck_dmi_table[] = {
 };
 
 
+#ifdef CONFIG_X86
 static int set_copy_dsdt(const struct dmi_system_id *id)
 {
 	printk(KERN_NOTICE "%s detected - "
@@ -97,8 +98,14 @@ static struct dmi_system_id dsdt_dmi_table[] __initdata = {
 		DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
 		DMI_MATCH(DMI_PRODUCT_NAME, "Satellite L505D"),
 		},
-	}
+	},
+	{}
 };
+#else
+static struct dmi_system_id dsdt_dmi_table[] __initdata = {
+	{}
+};
+#endif
 
 /* --------------------------------------------------------------------------
                                 Device Management