EX-5406 lipe: fix some compatibility issue in lpcc

EX-5406 lipe: fix some compatibility issue in lpcc

- use absolute path of program in lpcc.service
- replace yaml.load() with yaml.safe_load()

Signed-off-by: Lei Feng <flei@whamcloud.com>
Test-Parameters: trivial testlist=sanity-pcc
Change-Id: Iad3fa408f5b19e7370c0a5b069ad7637611118a7
Reviewed-on: https://review.whamcloud.com/47678
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>