ACPI: catch calls of acpi_driver_data on pointer of wrong type

Catch attempts to use of acpi_driver_data on pointers of wrong type.

akpm: rewritten to use proper C typechecking and remove the
"function"-used-as-lvalue thing.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/ac.c b/drivers/acpi/ac.c
index 831883b..8b6a84a 100644
--- a/drivers/acpi/ac.c
+++ b/drivers/acpi/ac.c
@@ -269,7 +269,7 @@
 	ac->device = device;
 	strcpy(acpi_device_name(device), ACPI_AC_DEVICE_NAME);
 	strcpy(acpi_device_class(device), ACPI_AC_CLASS);
-	acpi_driver_data(device) = ac;
+	device->driver_data = ac;
 
 	result = acpi_ac_get_state(ac);
 	if (result)