Adds bl2 with FIP to the build required for mbed Linux booting where
we do:
BootROM -> SPL -> BL2 -> OPTEE -> u-boot
If NEED_BL2 is specified then BL2 will be built and BL31 will have its
address range modified upwards to accommodate. BL31 must be loaded from a
FIP in this case.
If NEED_BL2 is not specified then the current BL31 boot flow is unaffected
and u-boot SPL will load and execute BL31 directly.
Signed-off-by: Ying-Chun Liu (PaulLiu) <paulliu@debian.org>
Change-Id: I78914d6002755f733ea866127cb47982a00f9700