net: e1000: Drop e1000_eth_ids[]

e1000_eth_ids holds compatible strings for e1000 devices, but it
is meaningless as e1000 is a PCI device and there is no such
compatible string assigned to e1000 by the DT bindings community.

Drop it.

Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Simon Glass <sjg@chromium.org>