docs: remove redundant Measured Boot interface info

A separate design document for Measured Boot covers the porting
guidelines for the Measured Boot interfaces. As a result,
the Measured Boot interfaces have been removed from the porting
guide and a link to the Measured Boot design document has been
provided.

Change-Id: Ia6bd2620d830aea6aececab4af7e10a6d737f025
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
1 file changed