net: stmmac: rename dwmac4_tx_queue_routing() to match reality

Looking at dwmac4_tx_queue_routing(), it is obvious that it
sets up rx queue routing.

Rename dwmac4_tx_queue_routing() to dwmac4_rx_queue_routing()
to better match reality.

Fixes: abe80fdc ("net: stmmac: RX queue routing configuration")
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>