Besides the rpi3.mk file itself, this also contains the additional
kconfig files and flags used when building Linux and U-Boot.

A set of firmware images are also included.

Signed-off-by: Joakim Bech <joakim.bech@linaro.org>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: David Brown <david.brown@linaro.org>