ad485x_fmcz: Add 3 wire SPI support for LVDS

[StancaPop]

PR Description

Add support for 3 wire SPI on the LVDS configuration of the ad485x_fmcz reference design.
Update the documentation by adding the THREE_W_SPI build parameter use case.

PR Type

• Bug fix (change that fixes an issue)
• New feature (change that adds new functionality)
• Breaking change (has dependencies in other repos or will cause CI to fail)
• Documentation

PR Checklist

• I have followed the code style guidelines
• I have performed a self-review of changes
• I have compiled all hdl projects and libraries affected by this PR
• I have tested in hardware affected projects, at least on relevant boards
• I have commented my code, at least hard-to-understand parts
• I have signed off all commits from this PR
• I have updated the documentation (wiki pages, ReadMe files, Copyright etc)
• I have not introduced new Warnings/Critical Warnings on compilation
• I have added new hdl testbenches or updated existing ones

[IuliaCMoldovan]

Suggested change

	# AD485X-FMCZ HDL Project
	# AD485X-FMCZ/Zed HDL Project

Just noticed (from another project) that it would be good to have it. I will update the template to state this, as well as the other discussed points

[StancaPop]

Done