staging: lustre: remove memset(0) after LIBCFS_ALLOC

Joe Perches mentioned on driverdev-devel that memset after LIBCFS_ALLOC
is not necessary as it is already done during LIBCFS_ALLOC_POST. This
commit removes these unnecessary memsets. Based on the results of running
a cocci patch along the lines of:

@@
expression E1, E2;
@@

LIBCFS_ALLOC (E1,E2);
...
- memset(E1,0,E2);

Signed-off-by: Vitaly Osipov <vitaly.osipov@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>