spapr: Remove some non-useful properties on DRC objects

spapr: Remove some non-useful properties on DRC objects

 * 'connector_type' is easily derived from the 'index' property, so there's
   no point to it (it's also implicit in the QOM type of the DRC)
 * 'isolation-state', 'indicator-state' and 'allocation-state' are
   part of the transaction between qemu and guest during PAPR hotplug
   operations, and outside tools really have no business looking at it
   (especially not changing, and these were RW properties)
 * 'entity-sense' is basically just a weird PAPR encoding of whether there
   is a device connected to this DRC

Strictly speaking removing these properties is breaking the qemu interface.
However, I'm pretty sure no management tools have ever used these.  For
debugging there are better alternatives.  Therefore, I think removing these
broken interfaces is the better option.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Acked-by: Michael Roth <mdroth@linux.vnet.ibm.com>