[PATCH] Two more minor patches for i8253_cascade_ns_to_timer_2div

Here's a couple more minor patches for the 
i8253_cascade_ns_to_timer_2div function, which I should have spotted 
earlier.

8253_dupcalc.patch gets rid of a duplicate calculation
8253_overflow.patch adds some arithmetic overflow checks to the "early 
exit" test.

-- 
-=( Ian Abbott _at_ MEV Ltd.    E-mail: <abbotti_at_mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-