Input: synaptics-rmi4 - unlock on error

We should unlock before returning on this error path.

Fixes: 3a762dbd ('[media] Input: synaptics-rmi4 - add support for F54 diagnostics')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>