counter: 104-quad-8: Make quad8_ops static

Fix sparse warning:

drivers/counter/104-quad-8.c:836:26: warning:
 symbol 'quad8_ops' was not declared. Should it be static?

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>