MIPS: DEC: Rate-limit memory errors for non-KN01 parity systems

MIPS: DEC: Rate-limit memory errors for non-KN01 parity systems

Similarly to memory errors in ECC systems also rate-limit memory parity
errors for KN02-BA, KN02-CA, KN04-BA, KN04-CA DECstation and DECsystem
models.  Unlike with ECC these events are always fatal and are less
likely to cause a message flood, but handle them the same way for
consistency.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>