[PATCH][XFRM]: Convert a few __u8 to proper u8

Ok, here it is. 2.6.20 material but dependent on all the other patches
I have posted.

Ok, this ipsec thing is distracting me from the 2 generic netlink
presentations i am trying to get started on for Foss.in (For once i
thought i was organized - worse, Harald will kill me if i dont have it
done).
Actually i still have one more on aevents that i wanted to talk about;
but maybe i should leave that to later.

cheers,
jamal