arm64: dts: ti: k3-j721s2: Move aliases to board dts

Aliases are board specific and should be in board dts files.
So, move aliases to board dts and trim the list to interfaces that are
actually enabled.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Kishon Vijay Abraham I <kishon@ti.com>
Link: https://lore.kernel.org/r/20211223121650.26868-2-vigneshr@ti.com