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.

Example btmon: firmware debug log.
1. Enable firmware debug log.
< HCI Command: Vendor (0x3f|0x005d) plen 4
        00 00 02 02                                      ....
> HCI Event: Command Complete (0x0e) plen 8
      Vendor (0x3f|0x005d) ncmd 1
        Status: Success (0x00)
        00 00 02 02                                      ....
2. Diagnostic packet from controller
= Vendor Diagnostic (len 500)
          ff 05 f0 01 fd ff 02 0e 08 01 5d fc 00 00 00 02
          02 aa aa aa cb e3 f0 15 b0 0c 5f 01 00 d1 0f 33
          01 7f 00 08 57 61 0c 00 00 00 00 00 23 37 17 00
          fd ff 00 00 29 60 ff ff b1 56 e8 00 57 40 0a 40
          39 95 f2 00 47 40 43 00 fc f0 16 00 57 61 0c 00
          00 00 00 00 23 37 17 00 fd ff 00 00 29 60 ff ff
          65 95 f2 00 57 40 0a 40 ec d3 fc 00 47 40 3b 00
          2c f1 17 00 57 61 0c 00 00 00 00 00 23 37 17 00
          fd ff 00 00 29 60 ff ff 19 d4 fc 00 57 40 76 1c
          b2 61 01 01 47 40 b3 04 0b 63 18 00 fe ff 02 01
          04 05 33 8b 9e 08 00 aa aa aa aa aa 27 38 01 02
          01 00 00 00 02 e0 10 00 20 00 20 00 2a 08 40 00
          20 00 20 08 2a 08 02 00 40 00 00 01 2e 08 40 00
          01 67 b0 c2 2e 08 3e 07 ff ff ff ff 40 08 01 00
          02 00 00 00 34 08 a3 00 00 00 00 00 34 08 a3 00
          00 00 00 00 35 08 45 01 00 00 00 00 2e 08 40 00
          01 67 b0 c2 30 35 01 02 00 00 00 00 2c 31 01 00
          02 00 00 40 2d 19 03 00 00 40 00 00 fd ff 02 0f
          04 00 01 01 04 aa aa aa aa aa aa aa 57 61 0c 00
          00 00 00 00 23 46 32 00 01 00 00 00 2f 35 00 02
          00 00 00 00 29 35 ff 02 00 22 00 00 2d 31 a6 02
          02 00 00 00 31 6c 40 00 14 63 18 1b 31 6c 40 00
          14 63 18 23 51 08 53 00 12 63 18 00 2c 35 12 01
          fe 00 00 00 2b 35 fe 02 02 00 00 00 2f 31 21 00
          00 00 02 00 75 61 01 00 4c 1b 93 00 79 61 01 00
          00 00 00 00 12 e3 63 18 20 31 86 01 74 61 68 03
          00 00 04 00 a1 73 ff 00 b9 01 00 00 a1 73 04 00
          00 00 00 00 a1 73 00 00 00 00 00 00 a1 73 00 00
          02 00 00 00 31 6c 40 00 16 63 18 0c 31 6c 40 00
          16 63 18 1c 77 61 40 00 48 33 40 00 14 e3 63 18
          40 31 86 01 00 d1 02 c5 07 23 a1 34 73 61 37 02
          02 00 00 a1

Signed-off-by: mark-yw.chen <mark-yw.chen@mediatek.com>
Reviewed-by: Michael Sun <michaelfsun@google.com>
Reviewed-by: Archie Pusaka <apusaka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>