Fix typo in installation of vmware virtdriver

The probably got introduced in recent adjustments to cleanup the
virt driver installs.

Change-Id: Ic51411d5bd9b18d395dbdf948c58fea2d53eba0d
diff --git a/lib/ceilometer b/lib/ceilometer
index d7888d9..ed9b933 100644
--- a/lib/ceilometer
+++ b/lib/ceilometer
@@ -341,7 +341,7 @@
         fi
 
         if [[ "$VIRT_DRIVER" = 'vsphere' ]]; then
-            pip_instal_gr oslo.vmware
+            pip_install_gr oslo.vmware
         fi
     fi