configs/acmesystems_acqua_a5: new defconfigs

configs/acmesystems_acqua_a5: new defconfigs

The Acqua A5 is a system on module based on the Microchip SAMA5D31 SoC:

    https://www.acmesystems.it/acqua

It is available in both 256 MiB and 512 MiB versions, hence the two
defconfig files. These configs build microSD card images with:

    - AT91Bootstrap 3
    - Linux 5.4.107
    - default buildroot packages (uClibc, Busybox)

The device tree blob comes from Acme Systems:

    https://github.com/AcmeSystems/dts-archive

It is licensed under GPLv2 or later.

Signed-off-by: Edgar Bonet <bonet@grenoble.cnrs.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>