LU-9859 libcfs: use round_up directly

LU-9859 libcfs: use round_up directly

The macro cfs_size_round() is just round_up(val, 8). Replace
cfs_size_round() with the Linux standard round_up().

Change-Id: I5a5ba4e663672c0b0bba5c99be9e0bece2dc3c87
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50545
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>