Unix CM: Don't cast allocator returns

Unix CM: Don't cast allocator returns

All of our allocators return (void *) values, so there is no need
to cast the returns - doing so is just noise.

Change-Id: I6b1009efbb5034225a4af0e19d03b74c628dfb82
Reviewed-on: http://gerrit.openafs.org/7457
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>