Trivial patchlet...ethtool core already caps regs.len at a max of
->get_regs_len():

	reglen = ops->get_regs_len(dev);
	if (regs.len > reglen)
		regs.len = reglen;

So doing the same in the in de2104x driver ->get_regs() is redundant.
Patch below simply removes it to clarify the guarantee of the API.