board: sk-am69: Define capsule update firmware info
Define the firmware components updatable via EFI capsule update, including
defining capsule GUIDs for the various firmware components for the AM69
SK.
TODO: possibly make the struct's sk specific.
TODO: add doc commit (and make sure doc is sk/NOR specific, and add OSIP
boot mode)
TODO: update doc to show sk defconfig when building
Signed-off-by: Jonathan Humphreys <j-humphreys@ti.com> Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>