Bluetooth: msft: Fix compilation when CONFIG_BT_MSFTEXT is not set

This fixes compilation when CONFIG_BT_MSFTEXT is not set.

Fixes: 6b3d4c8fcf3f2 ("Bluetooth: hci_event: Use of a function table to handle HCI events")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>