afs: use void * for generic pointers in the nfs translator dispatcher

afs: use void * for generic pointers in the nfs translator dispatcher

Replace the use of char * and char ** with void * for representing
generic pointers in the nfs dispatcher functions.  This was done to fix
a large number of compile time warnings, and allows us to remove a
number of explicit casts.

Also, remove the unnecessary char * casts of memset and memcpy arguments in the
nfs translator dispatcher.

This commit fixes a large number of Solaris Studio warning messages in the
form:

  ... warning: argument #X is incompatible with prototype:

Change-Id: I42e2d40b8112ada9417724282c0230f48a40324f
Reviewed-on: https://gerrit.openafs.org/12989
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>