Marvell/Armada70x0Db: Enable building with NOOPT flag

Newly added boards can build with TARGET set to NOOPT,
so align the Armada70x0Db.

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