96boards: add support to 96boards (https://www.96boards.org/)

96boards: add support to 96boards (https://96boards.org/)

This patch adds support to 96boards. 96boards is an open platform
specification. This spec strandardizes the pins on the external
connectors like Low speed and High speed. Given these pins are standard
across multiple boards, I think adding a generic 96boards made sense to
me.

The idea behind adding this generic board file is to make mraa work on
most of the 96boards with minimal changes to board support in libmraa.

This patch adds support to the LS expansion connector which has got 12
gpio pins + 2 i2c + 1 spi and 2 uarts.

For now I have added Dragaon board DB401c support as part of this patch
and is tested.
More info about board @ https://www.96boards.org/products/ce/dragonboard410c/

Long term plan is to get all this configuration from the /sys and
populate the board specifics dynamically, which is bit easy with
96boards specs in-place.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>