ASoC: soc-core: remove always-false path

cppcheck throws the following warning:

sound/soc/soc-core.c:2773:6: style: Condition '!num_widgets' is always
false [knownConditionTrueFalse]
 if (!num_widgets) {
     ^

sound/soc/soc-core.c:2761:18: note: Assuming that condition
'num_widgets<0' is not redundant
 if (num_widgets < 0) {
                 ^
sound/soc/soc-core.c:2766:18: note: Assuming condition is false
 if (num_widgets & 1) {
                 ^
sound/soc/soc-core.c:2772:2: note: Compound assignment '/=', assigned
value is 0
 num_widgets /= 2;
 ^

We should check upfront all error conditions.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20220421162505.302132-1-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>