if_cgem: Cleanup compatible and add new ones

[manu]

Summary

• Remove cdns,gem, it's the generic binding but for all platform that include this one we need specific drivers setup so remove it.
• Remove cdns,macb, it's the generic binding for Atmel AT91 which we don't suport
• Remove cadence,gem, it's not an official binding and seems to be only used in some obscure ARM11 SoC.
• Note that the cdns,zynq* are deprecated
• Add the new Xilinx compatible for zynq and zynqmp

Sponsored by: Beckhoff Automation GmbH & Co. KG

[skibo]

I tried these changes on a Zybo and it works fine.

[bsd_dino.sk]

Tested together with D41857 on Zybo Z7 board, no problem with this change.