tty: stop defining STD_COM_FLAGS in drivers

STD_COM_FLAGS is mostly a bad name for what the drivers thinks it is.
Stop using it and pass the flags directly.

cyclades defines it as 0, so we do not assign anything to freshly
tty_port_init'ed structure.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>