Fix typo in cm_dcache.c

Fix typo in cm_dcache.c

Commit b85c5f9339e20d3de9b1316217dadbea41ad537e introduced a new
memset() but left out a prenthesis.

In the absence of a windows build machine, this error went unnoticed.

Reported by Mark Vitale.

Reviewed-on: https://gerrit.openafs.org/12241
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 808b156bd890cd78dc59b443b4ebe32e98d440d4)

Change-Id: I1e8ac9c0edaf38212c63b662af227f4c1ef9603f
Reviewed-on: https://gerrit.openafs.org/12252
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Tested-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>