tty: reformat TTY_DRIVER_ flags into kernel-doc

We want to reference TTY_DRIVER_* flags in Documentation/ later in this
series. But the current documentation in the TTY_DRIVER_*'s header does
not allow that. Reformat it to kernel-doc using "DOC" directive and
line-feeds, so that we can include it as it is.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211126081611.11001-11-jslaby@suse.cz


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