Added a firmware update metadata structure as per section 4.1
in the specification document[1].
Also, added the build options used in defining the firmware
update metadata structure.
[1]: https://developer.arm.com/documentation/den0118/a/
Change-Id: I8f43264a46fde777ceae7fd2a5bb0326f1711928
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>