buildimage: Add gearbox phy device files and a new physyncd docker to…

[sydlogan]

… support VS gearbox phy feature

• scripts and configuration needed to support a second syncd docker (physyncd)
• physyncd supports gearbox device and phy SAI APIs.
• support for VS target (sonic-sairedis vslib has been extended to support a virtual BCM81724 gearbox PHY).

HLD is located at https://github.com/Azure/SONiC/blob/b817a12fd89520d3fd26bbc5897487928e7f6de7/doc/gearbox/gearbox_mgr_design.md

Signed-off-by: syd.logan@broadcom.com

- Why I did it

This work is part of the gearbox phy joint effort between Microsoft and Broadcom.

- How I did it

Overall feature was implemented across several projects. The collective pull requests (some in late stages of review at this point:

sonic-net/sonic-utilities#931 - CLI
sonic-net/sonic-swss-common#347 - Minor changes
sonic-net/sonic-swss#1321 - gearsyncd, config parsers, changes to orchargent to create gearbox phy on supported systems
sonic-net/sonic-sairedis#624 - physyncd, virtual BCM81724 gearbox phy added to vslib

- How to verify it

In a vslib build:

root@sonic:/home/admin# show gearbox interfaces status
PHY Id Interface MAC Lanes MAC Lane Speed PHY Lanes PHY Lane Speed Line Lanes Line Lane Speed Oper Admin

---

   1   Ethernet48  121,122,123,124               25G  200,201,202,203               25G       204,205                50G    down     down
   1   Ethernet49  125,126,127,128               25G  206,207,208,209               25G       210,211                50G    down     down
   1   Ethernet50      69,70,71,72               25G  212,213,214,215               25G           216               100G    down     down

In addition, docker ps | grep phy should show a physyncd docker running.