staging: lustre: discard cfs_time_before_64()

cfs_time_before_64 is the same as time_before64()
similarly cfs_time_beforeq_64() matsches time_before_eq64()
So just use the standard interfaces.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>