configs: rpi: add support for Ubuntu Server images

Ubuntu Server images actually use U-boot by default on RPi3 and the
layout and naming of the files is slightly different on the boot partition.
That is why we need additional logic here to determinant what we are converting

Changelog: Add support for Ubuntu Server images on Raspberry Pi 3

Signed-off-by: Mirza Krak <mirza.krak@northern.tech>

configs/raspberrypi_config

@@ -43,12 +43,22 @@ function platform_modify() {
   # the service.
   run_and_log_cmd "sudo ln -sf /dev/null work/rootfs/etc/systemd/system/udisks2.service"
 
+  # Ubuntu Server images actually use U-boot by default on RPi3 and the
+  # layout is slightly different on the boot partition. That is why we need
+  # additional logic here to determinant what we are converting.
+  if [ -e work/boot/uboot.bin ] && [ -e work/boot/vmlinuz ]; then
+    RASPBERRYPI_KERNEL_IMAGE="vmlinuz"
+    RASPBERRYPI_BOOTLOADER_IMAGE="uboot.bin"
+  else
+    RASPBERRYPI_BOOTLOADER_IMAGE="${RASPBERRYPI_KERNEL_IMAGE}"
+  fi
+
   # Extract Linux kernel and install to /boot directory on rootfs
   run_and_log_cmd "sudo cp work/boot/${RASPBERRYPI_KERNEL_IMAGE} work/rootfs/boot/${MENDER_KERNEL_IMAGETYPE}"
 
   # Replace kernel with U-boot and add boot script
   run_and_log_cmd "sudo mkdir -p work/rootfs/uboot"
-  run_and_log_cmd "sudo cp work/rpi/binaries/u-boot.bin work/boot/${RASPBERRYPI_KERNEL_IMAGE}"
+  run_and_log_cmd "sudo cp work/rpi/binaries/u-boot.bin work/boot/${RASPBERRYPI_BOOTLOADER_IMAGE}"
   run_and_log_cmd "sudo cp work/rpi/binaries/boot.scr work/boot"
   run_and_log_cmd "sudo cp work/rpi/binaries/fw_env.config work/rootfs/etc/"