Create caskroom/homebrew-drivers

[radeksimko]

As mentioned earlier on IRC channel + mentioned here, there seems to be a number of casks for system drivers and this amount may grow over time.

$ brew cask search driver

==> Partial matches
d235j-xbox360-controller-driver        ftdi-vcp-driver                silicon-labs-vcp-driver            xbox360-controller-driver
fender-amp-drivers             prolific-usb-serial-driver         wch-ch34x-usb-serial-driver

so I suggest creating caskroom/homebrew-drivers and moving the existing ones over.
Any objections/suggestions?

[radeksimko]

After rereading #5876 , closing this & reopening that one as it's more generic and explains the whole problem better.