I'm sorry for late response, as I do not often use GRML 

Unfortunately, there is no such file, 

grml@grml ~ % ll /sys/devices/platform/sony-laptop
total 0
lrwxrwxrwx 1 root root    0 Sep 26 09:26 driver -> ../../../bus/platform/drivers/sony-laptop/
-r--r--r-- 1 root root 4096 Sep 26 09:26 modalias
drwxr-xr-x 2 root root    0 Sep 26 09:26 power/
lrwxrwxrwx 1 root root    0 Sep 26 09:22 subsystem -> ../../../bus/platform/
-rw-r--r-- 1 root root 4096 Sep 26 09:22 uevent

I just removed the module, and it seems that everything works fine

Thanks