Publish all repositories required to build the image

[rnadyrshin]

Now
We want our contributors to be able to build the OS image using public repositories. Now rkbin and rockchip-linux are private.

• Clarify Rockchip’s policy on distribution of the rkbin and publish it if permitted.
• Decide what to do with the BSP kernel; if we keep it in the image by default, ensure it is also published.

[alchark]

@zhovner let's discuss how we move forward on this one. It would indeed be good to publish them both