Use more granular lock in BaseDriverFactory
Use more granular lock in BaseDriverFactory

There is no need to lock the whole driver loading, it's enough to lock
per entry point type. It's actually questionable that we need a lock at
all, but I'll leave it for another time.

Change-Id: Ib2b16bf99e072546bcca3be357613282edfe99a8

openstack/ironic,openstack/ironic