Increase the cpu and memory resource limits for Ceph OSDs

The minimium requirements for a Ceph OSD have changed in the latest
Luminous release to accomodate Bluestore changes. We need to support
these changes as we look into upgrading Ceph to the latest Luminous
and beyond releases.

Change-Id: I3eddffe73cfd188ff012db7c74702de6921711e7

ceph-osd/values.yaml

@@ -51,11 +51,11 @@ pod:
     enabled: false
     osd:
       requests:
-        memory: "512Mi"
-        cpu: "500m"
-      limits:
-        memory: "1024Mi"
+        memory: "2Gi"
         cpu: "1000m"
+      limits:
+        memory: "5Gi"
+        cpu: "2000m"
     tests:
       requests:
         memory: "10Mi"