Device enumeration patch

Hi @andersharrisson, @lucasmagalhaes

I'd like to apply this patch from @hinkokocevar to our XDMA driver packages (CentOS and Yocto). Either as a patch like this or by keeping a fork of the upstream repository and using that as the source for the package.

Hinko has a mirror repository here: https://gitlab.esss.lu.se/beam-diagnostics/fpga/dma_ip_drivers

The patch is from the "ess-fixes" branch

This patch changes how /dev/xdma* device nodes are enumerated.

Without it, the device indices depend on the order in which the
boards are discovered and initialized. This ordering might not
be consistent across reboots and changes if boards are added
or removed from the system.