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.

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I8b75121934c229dec8df7be0a4e69c1cda940d3f
Reviewed-on: https://review.whamcloud.com/36274
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>