LU-3963 Revert bitops changes

LU-3963 Revert bitops changes

This reverts bitops portions of http://review.whamcloud.com/7803
commit 001b8dbfacb747f1649a2eb047a5f118ce32fdc7

The uncovered problem is such that previously used fls returned 0
for the case of no bits set where as __fls return value
for such a case is undefined in the case of at least Linux kernel.

Change-Id: I993674161b08791157781a2b1da0872b12358bb1
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: http://review.whamcloud.com/9978
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>