Bluetooth: btusb: add callback function in btusb suspend/resume

Add suspend/resum callback function in btusb_data which are reserved
for vendor specific usage during suspend/resume. hdev->suspend will be
added before stop traffic in btusb_suspend and hdev-> resume will be
added after resubmit urb in btusb_resume.

Signed-off-by: Chris Lu <chris.lu@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>