staging: greybus: audio_module: remove redundant OOM message

All kmalloc-based functions print enough information on failure

Signed-off-by: Srikant Ritolia <s.ritolia@samsung.com>
Acked-by: Johan Hovold <johan@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>