net: ethernet: ti: am65-cpsw: Enable QSGMII mode for J721e CPSW9G

CPSW9G in J721e supports additional modes like QSGMII.
Add new compatible for J721e in am65-cpsw driver.

Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>