recipes-kernel: linux: Add support for selecting the right DTB from machine conf

Add variable KERNEL_DEVICETREE_NAME. It must be set from the machine
configuration file and contain the devicetree base name to be built.
Add machine configuration file for the MarsBoard RK3066
recipies-kernel: linux: Add initial support for the MarsBoard RK3066
recipies-kernel: linux: Make this recipe work with yocto next "dizzy"
recipies-kernel: linux: Switch to lastest upstream tag