CBD-1425:  fix typo in grommit symlink step

Change-Id: I291d9a8c2583ab1133fcb4f8b3d13c06642d3932
Reviewed-on: http://review.couchbase.org/40424
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>