Staging: lustre: mark a variable static in workitem.c

This fixes a sparse warning:
warning: symbol 'cfs_wi_data' was not declared. Should it be static?

Signed-off-by: Mike Sampson <mike@sambodata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/staging/lustre/lustre/libcfs/workitem.c
Simple merge