dell-wmi - fix condition to abort driver loading

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

The commit 1fdd407f incorrectly made driver
abort loading when known GUID is present when it should have done exactly
the opposite.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/platform/x86/dell-wmi.c

@@ -330,7 +330,7 @@ static int __init dell_wmi_init(void)
 	int err;
 	acpi_status status;
 
-	if (wmi_has_guid(DELL_EVENT_GUID)) {
+	if (!wmi_has_guid(DELL_EVENT_GUID)) {
 		printk(KERN_WARNING "dell-wmi: No known WMI GUID found\n");
 		return -ENODEV;
 	}