net: stmmac: dwmac4: report Rx checksum errors in status

Propagate hardware checksum failures from the descriptor parser to the
caller.

Currently, dwmac4_wrback_get_rx_status() updates stats when the Rx
descriptor signals an IP header or payload checksum error, but it does
not reflect this in its return value. The higher-level stmmac_rx() code
therefore cannot tell that hardware checksum validation failed.

Set the csum_none flag in the returned status when either
RDES1_IP_HDR_ERROR or RDES1_IP_PAYLOAD_ERROR is present. This aligns
dwmac4 with enh_desc_coe_rdes0() and lets stmmac_rx() mark the skb as
CHECKSUM_NONE for software verification.

This is a preparatory step for disabling the hardware filter that drops
frames which do not pass checksum validation.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20250818090217.2789521-3-o.rempel@pengutronix.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>