Bluetooth: btbcm: Read controller features during configuration

Read the Broadcom specific controller features during configuration and
print them for informational purposes.

  < HCI Command: Broadcom Read Controller Features (0x3f|0x006e) plen 0
  > HCI Event: Command Complete (0x0e) plen 12
        Broadcom Read Controller Features (0x3f|0x006e) ncmd 1
          Status: Success (0x00)
          Features: 0x07 0x00 0x00 0x00 0x00 0x00 0x00 0x00
            Multi-AV transport bandwidth reducer
            WBS SBC
            FW LC-PLC

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Szymon Janc <szymon.janc@codecoup.pl>