n_tty: drop fp from n_tty_receive_buf_real_raw()

The 'fp' parameter of n_tty_receive_buf_real_raw() is unused, so drop
it.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230712064216.12150-2-jirislaby@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>