checkpatch: add some common Blackfin checks

Add checks for Blackfin-specific issues that seem to crop up from time to
time.  In particular, we have helper macros to break a 32bit address into
the hi/lo parts, and we want to make sure people use the csync/ssync
variant that includes fun anomaly workarounds.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>