dt-bindings: phy: Add Cadence MHDP PHY bindings in YAML format.

- Add Cadence MHDP PHY bindings in YAML format.
- Add Torrent PHY reference clock bindings.
- Add sub-node bindings for each group of PHY lanes based on PHY type.
  Each sub-node includes properties such as master lane number, link reset,
  phy type, number of lanes etc.
- Add reset support including PHY reset and individual lane reset.
- Add a new compatible string used for TI SoCs using Torrent PHY.
This will not affect ABI as the driver has never been functional,
and therefore do not exist in any active use case.

Signed-off-by: Yuti Amonkar <yamonkar@cadence.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>