tty: tty_jobctrl: Fix 2 incorrectly documented functions

tty: tty_jobctrl: Fix 2 incorrectly documented functions

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

 drivers/tty/tty_jobctrl.c:33: warning: expecting prototype for tty_check_change(). Prototype was for __tty_check_change() instead
 drivers/tty/tty_jobctrl.c:97: warning: expecting prototype for proc_set_tty(). Prototype was for __proc_set_tty() instead

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210520121906.3468725-7-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>