Docs: some clean-up to platform folder

- Remove support platform list from integration guide. Only keep the
  list under platform folder.
  Otherwise platform vendors have to maintain two lists and information
  can be duplicated or misaligned.
- Refine Arm platform doc structure to put OpenAMP docs under
  Corstone-1000
- Refine Cypress PSoC64 doc structure to move library docs under the
  PSoC64 list.

Change-Id: I7fad8dd1eb52594d406f6be8a61c38c27fcb72ff
Signed-off-by: David Hu <david.hu@arm.com>
7 files changed