BL2: Add patches for mcuboot

Until the PR https://github.com/mcu-tools/mcuboot/pull/2305 is merged,
apply the added patches to support multiple signatures in mcuboot.

Signed-off-by: Maulik Patel <maulik.patel@arm.com>
Change-Id: Id8e62b7f332611858508bd445fab99fd7c0259ab
6 files changed