Removing myself as maintainer for allwinner and rpi boards

[viraniac]

Description

Removing myself as maintainer for Raspberry Pi and Allwinner boards as I no longer have time to maintain them. As some of the boards no longer have maintainer, changed them to csc.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules