mkrpm action has been removed in dkms #219

As of the 2.8.8 release, dkms has dropped support for distribution specific packaging. Running Fedora 35, I have version 3.0.3 installed, and dkms mkrpm fails in Droidcam's install-dkms script. I don't know if this is a problem, as the script seems to continue unperturbed, but it does throw an error message.