Fix typo in linux limits

https://mirantis.jira.com/browse/RIL-1037
diff --git a/linux/system/single.yml b/linux/system/single.yml
index fad25ae..7f51033 100644
--- a/linux/system/single.yml
+++ b/linux/system/single.yml
@@ -50,9 +50,9 @@
               item: nofile
               value: 307200
             - type: soft
-              item: noproc
+              item: nproc
               value: 307200
             - type: hard
-              item: noproc
+              item: nproc
               value: 307200