schema: Add rdma for host migrate transport capability

https://bugzilla.redhat.com/show_bug.cgi?id=1572491

Commit id 'b3fd95e3' added rdma as a valid option for
virCapabilitiesAddHostMigrateTransport, but didn't update
the capabilities schema resulting in possible virt-xml-validate
failure.

While at it, update the capabilityschemadata for caps-qemu-kvm
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>
ACKed-by Michal Privoznik <mprivozn@redhat.com>

docs/schemas/capability.rng

@@ -162,6 +162,7 @@
               <choice>
                 <value>vpxmigr</value>
                 <value>tcp</value>
+                <value>rdma</value>
               </choice>
             </element>
           </oneOrMore>

tests/capabilityschemadata/caps-qemu-kvm.xml

@@ -8,6 +8,7 @@
       <live/>
       <uri_transports>
         <uri_transport>tcp</uri_transport>
+        <uri_transport>rdma</uri_transport>
       </uri_transports>
     </migration_features>
     <topology>