libafs: Remove support for length optimisation

libafs: Remove support for length optimisation

At one point afs_StoreAllSegments had an optimisation to speed up
stores. However, that optimistation used the chunkLength without
taking appropriate locks, and was disabled. The variable assignments
which still exist from this code cause errors with gcc 4.6.0, so just
remove them.

Change-Id: I86547d94280d7f07214fbf6ef5b3db61c9781e59
Reviewed-on: http://gerrit.openafs.org/4991
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>