ASoC: samsung: odroid: Prevent uninitialized variable use

This addresses an issue pointed out by compiler warning:

sound/soc/samsung/odroid.c: In function ‘odroid_audio_probe’:
sound/soc/samsung/odroid.c:298:22: warning: ‘cpu_dai’ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  priv->clk_i2s_bus = of_clk_get_by_name(cpu_dai, "iis");
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>