ASoC: Fix warning while make xmldocs caused by soc-core.c

This patch fix following warning while make xmldocs.
Warning(.//sound/soc/soc-core.c:2148): No description found
for parameter 'ratio'

Add missing ":"

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-core.c

@@ -2127,7 +2127,7 @@ EXPORT_SYMBOL_GPL(snd_soc_codec_set_pll);
 /**
  * snd_soc_dai_set_bclk_ratio - configure BCLK to sample rate ratio.
  * @dai: DAI
- * @ratio Ratio of BCLK to Sample rate.
+ * @ratio: Ratio of BCLK to Sample rate.
  *
  * Configures the DAI for a preset BCLK to sample rate ratio.
  */