de4x5 fixes

* (trivial) endianness annotations
* don't bother with del_timer() from the inside of timer handler itself
* disable_ast() really ought to do del_timer_sync(), not del_timer()
* clean the timer handling in general.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>