There is noone setting nci_uart_ops::recv_buf, so the default one
(nci_uart_default_recv_buf) is always used. So drop this hook, move
nci_uart_default_recv_buf before the use in nci_uart_tty_receive and
remove unused parameter flags.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210302062214.29627-16-jslaby@suse.czSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>