ASoC: codecs: wcd938x: fix boolreturn.cocci warning

ASoC: codecs: wcd938x: fix boolreturn.cocci warning

Return statements in functions returning bool should use true/false
instead of 1/0.

Fix the following coccicheck warning:
./sound/soc/codecs/wcd938x.c:1190:9-10: WARNING: return of 0/1 in
function 'wcd938x_volatile_register' with return type bool.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/1623811535-15841-1-git-send-email-yang.lee@linux.alibaba.com
Signed-off-by: Mark Brown <broonie@kernel.org>