ASoC: Blackfin: cleanup sport handling in ASoC Blackfin AC97 code

- make sport number handling more dynamic as not all
  Blackfins have a linear sport map starting at 0
- indexes can be macroed away too

Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>