Docs: Clean up draft status claims

The design document status is optional. The status field in some design
documents are not changed during merge and are still "Draft".
It will confuse readers and developers as obviously those design
documents have been accepted.

Remove the "Draft" status from those design documents.

Change-Id: I94a2c049dc62fbf794d646d934a10e746400d224
Signed-off-by: David Hu <david.hu@arm.com>
4 files changed