When re-entering EDK2 from a high level OS such as Linux, the GICv3 may
be configured to use split priority drop and deactivate (EOImode == 1),
whereas EDK2's GICv3 driver assumes the default setting of EOImode == 0.
So clear the EOImode bit explicitly when taking control of the GIC.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2d2642f483