[PROPOSAL] Rework cmake integration for Zynq

- Merge pcp and host board settings
- Add comments with todos or proposals

Note: This commit is unfinished and not tested completely.

Missing:
- Apply changes to S6 CN demo

Change-Id: I2c4949285cbe6efe759e46485a193d5fdaa1e758
[FIX] Fix Zynq FSBL flags for reworked cmake integration

Change-Id: I4c5b87d74b19558531a785d01698f6a394944445
[TASK] Enable pcp's Microblaze settings

Change-Id: I421c3c181993a87ded53e9260d9964180cc35e61