MAINTAINERS: Fix up entry for Dell laptop SMM driver

Mark driver as maintained.
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Reviewed-by: NJean Delvare <jdelvare@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -3012,6 +3012,7 @@ F:	drivers/platform/x86/dell-laptop.c
 
 DELL LAPTOP SMM DRIVER
 M:	Guenter Roeck <linux@roeck-us.net>
+S:	Maintained
 F:	drivers/char/i8k.c
 F:	include/uapi/linux/i8k.h