* [202012] Add SOC property to enable AN/LT on some platforms
Why I did it
To enable autonegotiation/link training on some Broadcom-based platforms (Arista 7060CX, 7260CX3, 7050cx3, Celestica DX010)
How I did it
Add appropriate SOC property for enabling the feature to the Broadcom config files of appropriate platforms
Also convert line endings to UNIX format for one Celestica file
* Add 'phy_an_lt_msft' to BCM config file permitted list
* 7260cx3 DualToR config.bcm support based on DualToR setting in device metadata at boot time.
For HWSKU Arista-7260CX3-C64 the MMU setting SOC for T0/T1 is also combined into the config.bcm.j2 logic so use just one config file and adding delta based on Switch Roles.
