If you look at the Network Inventory in the vSPhere client, you'll notice that dvSwitches are defined in the hidden "network" folder that is in the root of each datacenter. A dvSwitch is defined on the level of the datacenter.
What you could do to limit it to a specific cluster, is look at which ESXi are connected to a specific dvSwitch. And from these ESXi you are able to retrieve the cluster these ESXi belong to.
