Set QB_KERNEL_ROOT for zynq-generic
Set QB_KERNEL_ROOT for zynq-generic

This value is passed to the kernel in order to choose the correct disk
but defaults to /dev/vda which does not boot.

Signed-off-by: John Toomey <ccf6bc1da034a98a2f5664569c91e34fa67b86e5@xilinx.com>
Signed-off-by: Mark Hatle <41765ab18fb75e64ff0efe27f2ebcdb2d6f7e44e@amd.com>

Xilinx/meta-xilinx,Xilinx/meta-xilinx,Xilinx/meta-xilinx,Xilinx/meta-xilinx,Xilinx/meta-xilinx,Xilinx/meta-xilinx