ASoC: rt5682: remove useless assignments

cppcheck warnings:

sound/soc/codecs/rt5682.c:1234:6: style: Redundant initialization for
'idx'. The initialized value is overwritten before it is
read. [redundantInitialization]
 idx = rt5682_div_sel(rt5682, dmic_clk_rate, div, ARRAY_SIZE(div));
     ^
sound/soc/codecs/rt5682.c:1228:10: note: idx is initialized
 int idx = -EINVAL, dmic_clk_rate = 3072000;
         ^
sound/soc/codecs/rt5682.c:1234:6: note: idx is overwritten
 idx = rt5682_div_sel(rt5682, dmic_clk_rate, div, ARRAY_SIZE(div));
     ^

sound/soc/codecs/rt5682.c:1263:6: style: Redundant initialization for
'idx'. The initialized value is overwritten before it is
read. [redundantInitialization]
 idx = rt5682_div_sel(rt5682, ref, div_f, ARRAY_SIZE(div_f));
     ^
sound/soc/codecs/rt5682.c:1248:25: note: idx is initialized
 int ref, val, reg, idx = -EINVAL;
                        ^
sound/soc/codecs/rt5682.c:1263:6: note: idx is overwritten
 idx = rt5682_div_sel(rt5682, ref, div_f, ARRAY_SIZE(div_f));
     ^

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210302212527.55158-24-pierre-louis.bossart@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>