Blackfin arch: rename blackfin_sram.c to sram-alloc.c

rename blackfin_sram.c to sram-alloc.c (we know it is a blackfin file,
since it is in arch/blackfin) - and there is no "driver" code in there,
it is just an allocator/deallocator for L1 and L2 sram.

Also fix a problem that checkpatch pointed out

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>