HID: gt683r: fix race condition

This will fix race condition noticed by Oliver Neukum. Sysfs files are
created before mutex and work are initialized.

Signed-off-by: Janne Kanniainen <janne.kanniainen@gmail.com>
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Bryan Wu <cooloney@gmail.com>