LU-13153 lib: fix llapi_get_version_string

LU-13153 lib: fix llapi_get_version_string

llapi_get_version_string() has always been broken as it passes args to
get_lustre_param_value in the wrong order.

Test-Parameters: trivial
Fixes: 0c5fbd80f1ba ("LU-5969 lustreapi: replace llapi_get_version()")
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ib4bdd715295f97fe5b7080f42bfa06883f191234
Reviewed-on: https://review.whamcloud.com/40680
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>