Bluetooth: btusb: Record debug log for Mediatek Chip.
Mediatek Bluetooth controller sends the FW log and FW dump via EP2.
This patch creates an MTK specified callback(btusb_recv_acl_mtk) to
replace the original one (hci_recv_frame) when an MTK controller is
detected. The new callback will separate the firmware dump traffics
from the ACL data to have them process separately.
1. Add a new field (recv_acl) to the btusb_data struct to store
vendor-specific ACL callback handler.
2. Add the MTK-specific ACL callback handler (btusb_recv_acl_mtk) to
process ACL data, debug log, and firmware dump.
3. The debug log traces LMP/LL events and connection quality reports.
4. The upper layer can use hci_channel_monitor to receive these
packets.