Handling indirect descriptors is a capability of the host and
not one that needs to be negotiated. Use the host capabilities
field and not the negotiated field when verifying that indirect
descriptors are supported.

Found with the Redhat Windows viostor driver, which clears
the indirect capability in the negotiated caps and then starts
using them.

Reported and tested by: Leon Dang (ldang@nahannisys.com)
MFC after: 2 weeks