gpio: sloppy-logic-analyzer: Check for error code from devm_mutex_init() call

Even if it's not critical, the avoidance of checking the error code
from devm_mutex_init() call today diminishes the point of using devm
variant of it. Tomorrow it may even leak something. Add the missed
check.

Fixes: 7828b7bb ("gpio: add sloppy logic analyzer using polling")
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20241030174132.2113286-3-andriy.shevchenko@linux.intel.com


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>