audit: do not needlessly take a lock in tty_audit_exit

We were doing spin_lock_irq and spin_unlock_irq.  This is STOOPID.

If we were in interupt context we were already screwed and called
panic() in do_exit().  So the irq stuff is useless.  Also, these values
can only be changed by receiving a netlink message from current.  Since
we are in do_exit() clearly we aren't in the syscall sending the netlink
message to change these values.  Thus, just read them and go with it.

Signed-off-by: Eric Paris <eparis@redhat.com>