HID: wiimote: narrow spinlock range in wiimote_hid_event()

In `wiimote_hid_event()`, the `wdata->state.lock` spinlock does not need
to be held while searching `handlers[]` for a suitable handler function.
Change it so the spinlock is only held during the call to the handler
function itself.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: David Rheinsberg <david.rheinsberg@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>