usb-serial: put subroutines in logical order

This patch (as1285) rearranges the subroutines in usb-serial.c
concerned with tty lifetimes into a more logical order: install, open,
hangup, close, release.  It also updates the formatting of the
kerneldoc comments.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>