Blackfin: debug-mmrs: include RSI_PID[4567] MMRs

The documentation is a little iffy as to whether these are actual MMRs,
but reading them on the hardware works, and the previous version of this
logic (the SDH) had PID[4567].  So add it for RSI too.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>