Boot: Add measured boot record TLV to shared area

This patch provides an alternative implementation of the
boot_save_boot_status() function which can read the already CBOR encoded
measured boot record from the image manifest and writes it to the shared
data area (between the bootloader and runtime SW) instead of copying the
individual (not encoded) claims separately.

Add new ATTEST_BOOT_INTERFACE variable to the build system to be able to
switch between the two behaviours.

Change-Id: I9ee66a5174cb5b851a79262decd35192cae7cc27
Signed-off-by: David Vincze <david.vincze@arm.com>
7 files changed