edit-node: _setup_pki_entitlement() call missed communicate()

To create the self._instroot/etc/pki/entitlement before the mount bind
we should call communicate().

Change-Id: Ieb8fbc8ea81f15f94e227ef043f3699bc0f05b5b
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>