bluetooth: btusb: Initialize .owner field of force_poll_sync_fops

Initialize .owner field of force_poll_sync_fops to THIS_MODULE in order to
prevent btusb from being unloaded while its operations are in use.

Fixes: 800fe5ec ("Bluetooth: btusb: Add support for queuing during polling interval")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>