freedreno/crashdec: Initial a7xx support

There are more things to do, e.g. BV mempool dumping and estimating the BV location. However this is a good start.

The expanded register size is because the reglist includes registers from other cores and these are read the same as any other GPU register. Note that this is also the actual range of type4 packets, even though registers higher than 0xffff are all protected. Right now these are skipped on page faults but still read with the crashdumper for hangs.

The associated kernel series is at https://patchwork.freedesktop.org/series/129163/.