Bluetooth: Move hci_recv_frame and hci_recv_diag prototypes

The protoypes for hci_recv_frame and hci_recv_diag are in the wrong
location in the header file. Move them close to all the other hci_dev
related exported functions.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>