ASoC: cs42l43: Initialize ret in default case in cs42l43_pll_ev()

clang warns (or errors with CONFIG_WERROR=y):

  sound/soc/codecs/cs42l43.c:1371:2: error: variable 'ret' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
   1371 |         default:
        |         ^~~~~~~
  sound/soc/codecs/cs42l43.c:1377:9: note: uninitialized use occurs here
   1377 |         return ret;
        |                ^~~
  sound/soc/codecs/cs42l43.c:1349:9: note: initialize the variable 'ret' to silence this warning
   1349 |         int ret;
        |                ^
        |                 = 0
  1 error generated.

Initialize ret to 0 in the default case, as there was nothing to do for
other event types.

Closes: ClangBuiltLinux#1922
Fixes: fc918cb ("ASoC: cs42l43: Add support for the cs42l43")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20230823-cs42l43_pll_ev-init-ret-v1-1-5836f1ad5dad@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: nathanchance

sound/soc/codecs/cs42l43.c

@@ -1369,6 +1369,7 @@ static int cs42l43_pll_ev(struct snd_soc_dapm_widget *w,
 			clk_disable_unprepare(priv->mclk);
 		break;
 	default:
+		ret = 0;
 		break;
 	}