phy: ti: gmii-sel: Add support for CPSW9G GMII SEL in J721e

Each of the CPSW9G ports in J721e support additional modes like QSGMII.
Add a new compatible for J721e to support the additional modes.

In TI's J721e, each of the CPSW9G ethernet interfaces can act as a
QSGMII main or QSGMII-SUB port. The QSGMII main interface is responsible
for performing auto-negotiation between the MAC and the PHY while the rest
of the interfaces are designated as QSGMII-SUB interfaces, indicating that
they will not be taking part in the auto-negotiation process.

Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20221026074532.109220-4-s-vadapalli@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>