soc: apple: rtkit: Add register dump decoding to crashlog

When the coprocessor crashes, it's useful to get a proper register dump
so we can find out what the firmware was doing. Add a decoder for this.

Originally this had ESR decoding by reusing the ARM64 arch header for
this, but that introduces some module linking and cross-arch compilation
issues, so let's leave that out for now.

Reviewed-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Signed-off-by: Hector Martin <marcan@marcan.st>