extend_volume of libvirt/volume/fc should not use device_path

The connection_info['data']['device_path'] field is not always
available. In cases that it was not available, it would cause
the debug code to raise a KeyError instead of proceeding.

Other similar debug messages in the same file do not include
device_path. As a simple fix, just drop the device_path from
the log.

Closes-Bug: #1989894
Change-Id: I4218fb39ce80800be8c95da7132b3b74226ad10a

nova/virt/libvirt/volume/fibrechannel.py

@@ -79,7 +79,6 @@ class LibvirtFibreChannelVolumeDriver(libvirt_volume.LibvirtBaseVolumeDriver):
         """Extend the volume."""
         LOG.debug("calling os-brick to extend FC Volume", instance=instance)
         new_size = self.connector.extend_volume(connection_info['data'])
-        LOG.debug("Extend FC Volume %s; new_size=%s",
-                  connection_info['data']['device_path'],
+        LOG.debug("Extend FC Volume: new_size=%s",
                   new_size, instance=instance)
         return new_size