tty: tty_audit: Demote non-conformant kernel-doc headers

tty: tty_audit: Demote non-conformant kernel-doc headers

Fixes the following W=1 kernel build warning(s):

 drivers/tty/tty_audit.c:91: warning: Function parameter or member 'buf' not described in 'tty_audit_buf_push'
 drivers/tty/tty_audit.c:129: warning: Function parameter or member 'sig' not described in 'tty_audit_fork'
 drivers/tty/tty_audit.c:137: warning: Function parameter or member 'tty' not described in 'tty_audit_tiocsti'
 drivers/tty/tty_audit.c:137: warning: Function parameter or member 'ch' not described in 'tty_audit_tiocsti'
 drivers/tty/tty_audit.c:202: warning: Function parameter or member 'tty' not described in 'tty_audit_add_data'
 drivers/tty/tty_audit.c:202: warning: Function parameter or member 'data' not described in 'tty_audit_add_data'
 drivers/tty/tty_audit.c:202: warning: Function parameter or member 'size' not described in 'tty_audit_add_data'

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Miloslav Trmac <mitr@redhat.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104193549.4026187-16-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>