platform/x86: thinkpad_acpi: Take mutex in hotkey_resume

hotkey_status_set expects the hotkey_mutex to be held.
It seems like it was missed here and that gives lockdep
warnings while resuming.

Fixes: 38831ea ("platform/x86: thinkpad_acpi: use lockdep annotations")
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Dennis Bonke <admin@dennisbonke.com>
Link: https://lore.kernel.org/r/20230914130356.235912-1-admin@dennisbonke.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/thinkpad_acpi.c

@@ -4116,9 +4116,11 @@ static void hotkey_resume(void)
 {
 	tpacpi_disable_brightness_delay();
 
+	mutex_lock(&hotkey_mutex);
 	if (hotkey_status_set(true) < 0 ||
 	    hotkey_mask_set(hotkey_acpi_mask) < 0)
 		pr_err("error while attempting to reset the event firmware interface\n");
+	mutex_unlock(&hotkey_mutex);
 
 	tpacpi_send_radiosw_update();
 	tpacpi_input_send_tabletsw();