ofproto: Fix crash processing malformed Bundle Add message.

ofproto: Fix crash processing malformed Bundle Add message.

When an OpenFlow Bundle Add message is received, a bundle entry is
created and the OpenFlow message embedded in the bundle add message is
processed.  If any error is encountered while processing the embedded
message, the bundle entry is freed. The bundle entry free function
assumes that the entry has been populated with a properly formatted
OpenFlow message and performs some message specific cleanup actions .
This assumption does not hold true in the error case and OVS crashes
when performing the cleanup.

The fix is in case of errors, simply free the bundle entry without
attempting to perform any embedded message cleanup

Signed-off-by: Anju Thomas <anju.thomas@ericsson.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>