ARM: pxa: ssp: remove unnecessary warning on kzalloc() failure

The memory subsystem will already complain loudly enough in such cases.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>