MAINTAINERS: catch special Rockchip code locations

Add some more locations that aren't catched by the general wildcard.
This includes the devicetree files, clock directory, rk3x i2c driver,
everything in a third layer under drivers like iio/adc/rockchip_saradc.c
and the i2s driver.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Olof Johansson <olof@lixom.net>