net: phy: qcom: at803x: Add Qualcomm IPQ5018 Internal PHY support

net: phy: qcom: at803x: Add Qualcomm IPQ5018 Internal PHY support

The IPQ5018 SoC contains a single internal Gigabit Ethernet PHY which
provides an MDI interface directly to an RJ45 connector or an external
switch over a PHY to PHY link.

The PHY supports 10BASE-T/100BASE-TX/1000BASE-T link modes in SGMII
interface mode, CDT, auto-negotiation and 802.3az EEE.

Let's add support for this PHY in the at803x driver as it falls within
the Qualcomm Atheros OUI.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: George Moussalem <george.moussalem@outlook.com>
Link: https://patch.msgid.link/20250613-ipq5018-ge-phy-v5-2-9af06e34ea6b@outlook.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>