gpio: ljca: use devm_mutex_init() to simplify the error path and remove()

gpio: ljca: use devm_mutex_init() to simplify the error path and remove()

Destroying the mutexes is done at the end of remove() so switching to
devres does not constitute a functional change. Use devm_mutex_init()
and remove repetitions of mutex_destroy().

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20241008162416.85111-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>