uboot-imx

detect and setup solidrun hummingboard2

The hummingboard2 is slightly different to the cubox i and to the
hummingboard. The GPIO pin info to probe came from solidruns
for of u-boot on github.
https://github.com/SolidRun/u-boot-imx6/blob/imx6/board/solidrun/mx6_cubox-i/mx6_cubox-i.c#L569-L589
I have tested on a hummingboard-edge witha  imx6 solo and 512mb of
ram.

Signed-off-by: Dennis Gilmore <dgilmore@redhat.com>