Correct a typo in dictionary name
Correct a typo in dictionary name

At some point, bmc_handlers was mispelled, affecting graceful handling of
detecting a broken port.  Correct the mispelling.

Change-Id: I80e86b9d98fb211a3f1195658b93eaa5a2e88c61

openstack/pyghmi,stackforge/pyghmi,openstack/pyghmi