A small typo fixup
BTW, how do you like the subject to look like?

cheers,
jamal

[GENL] Multicast computation off by one

When using the first 32 groups, the multicast group to bit mapping
was off by one.

Signed-off-by: Jamal Hadi Salim
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>