Blackfin: fix length checking in kgdb_ebin2mem

The kgdb_ebin2mem() was decrementing the count variable to do parsing, but
then later still tries to use it based on its original meaning.  So leave
it untouched and use a different variable to walk the memory.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>