staging: lustre: libcfs: remove unused rounding functions.

These are all unused except cfs_size_round().
So discard the others, and use the kernel-standard round_up()
function to implement cfs_size_round().

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>