LU-9325 llog: replace simple_strtol with kstrtol

LU-9325 llog: replace simple_strtol with kstrtol

Eventually simple_strtol will be removed so replace its use in
the llog_ioctl code with kstrtoxxx() functions.

Change-Id: I55a4e97837a1d9e0134dde92f0c2380f07691ab9
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/32598
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>