freedreno/a6xx: Updates for a6xx gen3 and gen4

Some of the new regs aren't very well understood, as I haven't found any examples of the blob doing anything interesting with them yet.

This is at least enough to fix the remaining deqp-glesN fails on 7c3 and bring it up to parity with a618/a630. There are some other "magic registers" (ie. DBG_ECO, etc) that differ, but at least from a functional standpoint, they don't seem to matter (yet).

I've not started looking at vk yet, mainly because a6xx gen4 devices are in short supply at this point.