kernel InitPeerParams has bogus branching and dup code

kernel InitPeerParams has bogus branching and dup code

several of the mtu configuration cases for the kernel version
of InitPeerParams were bogus. clean up the function.
(a forthcoming change reworks this anyway, but..)

Change-Id: Ia4449d5cecc80cddae7d0f611186f48614b908ee
Reviewed-on: http://gerrit.openafs.org/2343
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>