ASoC: remove duplicated code on pxa-ssp.c

* We don't need to write the registers twice, remove the first write.
* DAIFMT_INV switch is duplicated inside DAIFMT_FORMAT switch, move it
  out.

(This patch is for Mark's for-2.6.32 branch, I have not checked if the
code is duplicated on current 2.6.30)

Signed-off-by: Daniel Ribeiro <drwyrm@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>