Blackfin: drop BF535-specific text for exception 0x2A (unaligned instruction)

We don't support the BF535 at all, and the exception 0x2A text specific to
it is pretty verbose and confusing (since the behavior is simply odd), so
punt it to keep the noise down.

Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>