Blackfin arch: Fix bug - do not overflow the buffer given to us which tends to...

Blackfin arch: Fix bug - do not overflow the buffer given to us which tends to happen when CONFIG_L1_MAX_PIECE is increased past its default

Singed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>