MAINTAINERS: add maintainers for ChromeOS EC sub-drivers

There are multiple ChromeOS EC sub-drivers spread in different
subsystems, as all of them are related to the Chrome stuff add
Benson and myself as a maintainers for all these sub-drivers.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Benson Leung <bleung@chromium.org>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Acked-by: Guenter Roeck <groeck@chromium.org>