Add initial support for Engicam Is.IoT MX6UL SOM board
with below features:
- U-Boot 2017.07-rc1
- Linux 4.11.5
- Default packages from buildroot

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
[Thomas: add host-dosfstools/host-mtools.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>