Make HostPath CSI driver persistent across restart.

The driver dynamically provisions its volumes in /tmp. To preserve the data
across driver restarts, the directory must be mapped to more persistent
place, /tmp on the host seems to be the safest choice.

test/e2e/testing-manifests/storage-csi/hostpath/hostpath-v0/csi-hostpathplugin.yaml

@@ -55,6 +55,8 @@ spec:
             - mountPath: /var/lib/kubelet/pods
               mountPropagation: Bidirectional
               name: mountpoint-dir
+            - mountPath: /tmp
+              name: tmp
       volumes:
         - hostPath:
             path: /var/lib/kubelet/plugins/csi-hostpath-v0
@@ -68,3 +70,7 @@ spec:
             path: /var/lib/kubelet/plugins
             type: Directory
           name: registration-dir
+        - name: tmp
+          hostPath:
+            path: /tmp
+            type: Directory

test/e2e/testing-manifests/storage-csi/hostpath/hostpath/csi-hostpathplugin.yaml

@@ -55,6 +55,8 @@ spec:
             - mountPath: /var/lib/kubelet/pods
               mountPropagation: Bidirectional
               name: mountpoint-dir
+            - mountPath: /tmp
+              name: tmp
       volumes:
         - hostPath:
             path: /var/lib/kubelet/plugins/csi-hostpath
@@ -68,3 +70,7 @@ spec:
             path: /var/lib/kubelet/plugins_registry
             type: Directory
           name: registration-dir
+        - name: tmp
+          hostPath:
+            path: /tmp
+            type: Directory