MAINTAINERS: Mika and me are designated reviewers for I2C DESIGNWARE

Jarkko is a main contact to handle i2c-designware driver. Move Mika and me to
designated reviewers which we actualy are.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>