Input: mousedev - remove BKL

There's no need for BKL in mousedev, relevan protection is provided by
a private mutex.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>