aw_gpio: Add support for H616

[thj]

Summary

This adds padconf files for the two gpio ranges on the H616 SOC and adds
the SOC include.

[mhorne]

FYI, there is a small set of allwinner manpages (aw_gpio(4), aw_mmc(4), etc.) that maintain the list of compatible strings and SOC_ALLWINNER_* options.

I am not sure how useful this is, given we don't document most FDT drivers in this way. But you might as well keep them updated as you commit this series.

[thj]

Thanks for the heads up I'll update those too.