arm64: dts: ti: k3-j721e-*: add DP & DP PHY

Add DT nodes for DisplayPort and DisplayPort PHY. The DP is Cadence MHDP
8546 and the PHY is a Cadence Torrent PHY with TI WIZ wrapper.

Also add the required phy link nodes in the board dts files.

A slight irregularity in the bindings is the DPTX PHY register block,
which is in the MHDP IP, but is needed and mapped by the PHY.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Rahul T R <r-ravikumar@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Aradhya Bhatia <a-bhatia1@ti.com>
Link: https://lore.kernel.org/r/20220429112639.13004-2-r-ravikumar@ti.com