ASoC: wm0010: Fix resource leak

If kzalloc() fails for `img' then we are going to leak the memory
for `out'.  We are freeing the memory of all the tx/rx transfers
but the tx/rx buf pointers will be NULL if we drop out earlier.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>