atu dump support for mediatek

From: Mori Hiroki <yamori813_at_yahoo.co.jp>
Date: Tue, 18 Apr 2023 23:46:03 UTC
Hi

I add atu dump support to mediatek soc.

Still not support flush.

https://github.com/ZRouter/freebsd-src/commit/50597bd76a22c73a4fe382b535344135aee495a4

Thanks

Hiroki Mori