MAINTAINERS: i2c-imx: take over maintainership

I would like to maintain the i2c-imx driver. Since I work with
different i.MX variants and have access to the hardware, I can spend
some time on the reviewing of this driver.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>