LU-12769 recovery: use monotonic timer

LU-12769 recovery: use monotonic timer

instead of real one. also use absolute values for timer.

One of the reasons for the move from jiffies based timer
to a hrtimer timer was to avoid the issue of time drift.
It was discovered due to test failures with recovery on
VMs that the high resolution wall clock can drift as well.
Moving to the monotonic clock for the hrtimer avoids this
drift completely and it is safe to use since the recovery
timestamp is not shared between nodes.

Lustre-change: https://review.whamcloud.com/36274
Lustre-commit: 06408a4ef381121fa58783026a0cf0a6b0fa479c

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I8b75121934c229dec8df7be0a4e69c1cda940d3f
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/36937
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>