ASoC: atmel_ssc: Don't try to free ssc if request failed

We should only call ssc_free() when ssc_request() succeeds or bad
things will happen.

Signed-off-by: Joachim Eastwood <joachim.eastwood@jotron.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>