platform/x86: thinkpad_acpi: check the return value of devm_mutex_init()

devm_mutex_init() can fail so check its return value.

Fixes: 38b9ab80 ("platform/x86: thinkpad_acpi: Move subdriver initialization to tpacpi_pdriver's probe.")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20250305103146.53221-1-brgl@bgdev.pl


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>