MAINTAINERS: add PHY-related files to Amlogic SoC file list

Add PHY-related files to the Amlogic SoC file list.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/38f87b22-d9a8-b8d8-ba7b-a2c2d7311b04@gmail.com


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>