lwp: Don't cast returns from malloc()

lwp: Don't cast returns from malloc()

malloc() returns a (void *) on all of our current platforms. So,
don't bother casting the return value before assigning it - it is
unnecessary noise.

Change-Id: Ie41f7b831f0ba70796649e2493e014fe44f1c39e
Reviewed-on: http://gerrit.openafs.org/7467
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>