net: phy: mscc: fix packet loss due to RGMII delays

Two deadly typos break RX and TX traffic on the VSC8502 PHY using RGMII
if phy-mode = "rgmii-id" or "rgmii-txid", and no "tx-internal-delay-ps"
override exists. The negative error code from phy_get_internal_delay()
does not get overridden with the delay deduced from the phy-mode, and
later gets committed to hardware. Also, the rx_delay gets overridden by
what should have been the tx_delay.

Fixes: dbb050d ("phy: mscc: Add support for RGMII delay configuration")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Harini Katakam <harini.katakam@amd.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230627134235.3453358-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: vladimiroltean

drivers/net/phy/mscc/mscc_main.c

@@ -563,9 +563,9 @@ static int vsc85xx_update_rgmii_cntl(struct phy_device *phydev, u32 rgmii_cntl,
 	if (tx_delay < 0) {
 		if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
 		    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
-			rx_delay = RGMII_CLK_DELAY_2_0_NS;
+			tx_delay = RGMII_CLK_DELAY_2_0_NS;
 		else
-			rx_delay = RGMII_CLK_DELAY_0_2_NS;
+			tx_delay = RGMII_CLK_DELAY_0_2_NS;
 	}
 
 	reg_val |= rx_delay << rgmii_rx_delay_pos;