Don't cast arguments to free()

Don't cast arguments to free()

free(3) is defined as:

    void free(void *ptr);

so there is no need to cast the pointer argument being past to it to
(char *), (void *), or whatever other randomness happened to be floating
through the author's mind. Remove all such casts, as they are just
noise.

Change-Id: Ib7c8c259d53e9ce74fc486cb0997360044795395
Reviewed-on: http://gerrit.openafs.org/7453
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>