Revert commit fb763d

This commit completely breaks the salt-master on all non-Linux systems:

fb763d9

Why?

_hw_data(osdata) is called before `osdata` includes the key 'kernel', resulting
in a KeyError.  Steps to reproduce:

(saltenv) $ salt-master -l debug

salt/grains/core.py

@@ -484,7 +484,6 @@ def _virtual(osdata):
     #   virtual
     #   virtual_subtype
     grains = {'virtual': 'physical'}
-    grains.update(_hw_data(grains))
 
     # Skip the below loop on platforms which have none of the desired cmds
     # This is a temporary measure until we can write proper virtual hardware