In order to interface with the underlying host zPCI device, we need
to know its function handle. Add a routine to grab this from the
vfio CLP capabilities chain.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Message-Id: <20220902172737.170349-3-mjrosato@linux.ibm.com>
[thuth: Replace free(info) with g_free(info)]
Signed-off-by: Thomas Huth <thuth@redhat.com>