Platform/AMD/OverdriveBoard: build capsule unconditionally

Remove the DO_CAPSULE conditionals so that the capsules are
always built. This fixes a build issue that exists currently,
since the IPv6 enabled version of IScsiDxe that we now include
depends on a library class that can only be resolved if building
with DO_CAPSULE=TRUE.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>