logos: Add Solidrun's logo

Let Solidrun's logo appear on Cuboxi and Hummingboard by default.

Signed-off-by: Rabeeh Khoury <rabeeh@solid-run.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Reviewed-by: Tom Rini <trini@konsulko.com>