Refresh the BeagleBone Black image

Barebox won't build (it complains about <linux/list.h> not found and I
cannot easily solve that), so let's go back to U-Boot.

The 2019.01 U-Boot release is buggy in its recognizing of partition
tables (`fatls` complains, for example), and the whole thing reverts to
a "legacy boot", so let's use the latest release, the 2019.07.

I'm also giving up on the g_cdc module because the board that I'm using
has a microUSB header for the debug console.

- FIXME: Properly distinguish between an SD-card boot and an eMMC boot
(right now it is hardcoded to boot from the SD card)
- FIXME: test Rauc updates once eMMC works
- FIXME: activate watchdog from U-Boot

Change-Id: I013f145cf2fe24e41ea0dafd225e3feb1854712c
diff --git a/board/czechlight/beaglebone/create-uEnv.sh b/board/czechlight/beaglebone/create-uEnv.sh
new file mode 100755
index 0000000..9808fdd
--- /dev/null
+++ b/board/czechlight/beaglebone/create-uEnv.sh
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+install -m 0644 -D $BINARIES_DIR/boot.scr $TARGET_DIR/boot/boot.scr
+
+# prepare the static script with RAUC logic
+${HOST_DIR}/bin/mkimage -C none -A arm -T script \
+        -d ${BR2_EXTERNAL_CZECHLIGHT_PATH}/board/czechlight/beaglebone/rauc.scr.txt ${BINARIES_DIR}/rauc.scr
+
+# ...and a simplified one for SD-card booting (no image determination)
+${HOST_DIR}/bin/mkimage -C none -A arm -T script \
+        -d ${BR2_EXTERNAL_CZECHLIGHT_PATH}/board/czechlight/beaglebone/sd.scr.txt ${BINARIES_DIR}/sd.scr