cdc-acm: fix BREAK rx code path adding necessary calls

commit 08dff274 upstream.

Counting break events is nice but we should actually report them to
the tty layer.

Fixes: 5a6a62bd

 ("cdc-acm: add TIOCMIWAIT")
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20210311133714.31881-1-oneukum@suse.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>