phy: cadence: torrent: add support for three or more links using 2 protocols

phy: cadence: torrent: add support for three or more links using 2 protocols

This is a port of the corresponding commit in the Linux kernel which
adds the same support for the Cadence Torrent driver[0]. The commit
message below is taken as-is from the Linux kernel commit being ported.

The Torrent SERDES can support at most two different protocols (PHY types).
This only mandates that the device-tree sub-nodes used to represent the
configuration should describe links with at-most two different protocols.

The existing implementation however imposes an artificial constraint that
allows only two links (device-tree sub-nodes). As long as at-most two
protocols are chosen, using more than two links to describe them in an
alternating configuration is still a valid configuration of the Torrent
SERDES.

A 3-Link 2-Protocol configuration of the 4-Lane SERDES can be:
Lane 0 => Protocol 1 => Link 1
Lane 1 => Protocol 1 => Link 1
Lane 2 => Protocol 2 => Link 2
Lane 3 => Protocol 1 => Link 3

A 4-Link 2-Protocol configuration of the 4-Lane SERDES can be:
Lane 0 => Protocol 1 => Link 1
Lane 1 => Protocol 2 => Link 2
Lane 2 => Protocol 1 => Link 3
Lane 3 => Protocol 2 => Link 4

[0] https://github.com/torvalds/linux/commit/5b7b83a9839be643410c31d56f17c2d430245813

Signed-off-by: Hrushikesh Salunke <h-salunke@ti.com>