virsh: Support SCSI_GENERIC cap flag for nodedev-list

Document for nodedev-list is also updated.

tools/virsh-nodedev.c

@@ -453,6 +453,9 @@ cmdNodeListDevices(vshControl *ctl, const vshCmd *cmd ATTRIBUTE_UNUSED)
         case VIR_NODE_DEV_CAP_VPORTS:
             flags |= VIR_CONNECT_LIST_NODE_DEVICES_CAP_VPORTS;
             break;
+        case VIR_NODE_DEV_CAP_SCSI_GENERIC:
+            flags |= VIR_CONNECT_LIST_NODE_DEVICES_CAP_SCSI_GENERIC;
+            break;
         default:
             break;
         }

tools/virsh.pod

@@ -2118,9 +2118,9 @@ List all of the devices available on the node that are known by libvirt.
 I<cap> is used to filter the list by capability types, the types must be
 separated by comma, e.g. --cap pci,scsi, valid capability types include
 'system', 'pci', 'usb_device', 'usb', 'net', 'scsi_host', 'scsi_target',
-'scsi', 'storage', 'fc_host', 'vports'. If I<--tree> is used, the output
-is formatted in a tree representing parents of each node. I<cap> and
-I<--tree> are mutually exclusive.
+'scsi', 'storage', 'fc_host', 'vports', 'scsi_generic'. If I<--tree> is
+used, the output is formatted in a tree representing parents of each node.
+I<cap> and I<--tree> are mutually exclusive.
 
 =item B<nodedev-reattach> I<nodedev>