LU-6142 libcfs: discard PO2_ROUNDUP_TYPED, LOWEST_BIT_SET

LU-6142 libcfs: discard PO2_ROUNDUP_TYPED, LOWEST_BIT_SET

LOWEST_BIT_SET() is never used.

PO2_ROUNDUP_TYPED() has the same function as 'round_up()'.

osd_roundup2blocksz() can be further simplified using
DIV_ROUND_UP_ULL().

Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I075328ec935eef49d3aeaf5ea1b79b943aadfa2e
Reviewed-on: https://review.whamcloud.com/40859
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>