net: qcom/emac: remove unused address arrays

The EMAC is capable of multiple TX and RX rings, but the driver only
supports one ring for each.  One function had some left-over unused
code that supports multiple rings, but all it did was make the code
harder to read.

Signed-off-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>