imgs/boot: fix prepare_turris_image script for Mox and improve

This makes this script support Mox as well as it reduces unnecessary
spam it creates in logs.

imgs/boot/bin/prepare_turris_image

 #!/bin/bash
-set -e
+set -eu
 TFTP_ROOT="/var/tftpboot"
 
-branch="${1:-hbk}"
+board="$1"
+branch="${2:-hbk}"
+
+case "$board" in
+	omnia)
+		kernel="zImage"
+		dtb="dtb"
+		;;
+	mox)
+		kernel="Image"
+		dtb="armada-3720-turris-mox.dtb"
+		;;
+	*)
+		echo "Unsupported board: $board" >&2
+		exit 1
+		;;
+esac
 
 # Get appropriate medkit
 wait4network
-wget "https://repo.turris.cz/$branch/medkit/omnia-medkit-latest.tar.gz" -O medkit.tar.gz
+url="https://repo.turris.cz/$branch/medkit/$board-medkit-latest.tar.gz"
+echo "Getting medkit from:" "$url"
+wget -q "$url" -O medkit.tar.gz
 
 # Repack as CPIO
 mkdir root
@@ -16,9 +34,9 @@ ln -sf /sbin/init root/init
 mkimage -A arm -O linux -T ramdisk -C none -d root.cpio root.uimage
 
 # Prepare to TFTP
-cp root/boot/zImage "$TFTP_ROOT/zImage"
-cp -L root/boot/dtb "$TFTP_ROOT/dtb"
-mv root.uimage "$TFTP_ROOT/root.uimage"
+cp "root/boot/$kernel" "$TFTP_ROOT/"
+cp -L "root/boot/$dtb" "$TFTP_ROOT/"
+mv root.uimage "$TFTP_ROOT/"
 
 # Clean after ourself
 rm -rf root root.cpio medkit.tar.gz

nsfarm/board/_board.py

@@ -77,7 +77,7 @@ class Board(abc.ABC):
         # Now load image from TFTP
         with Container(lxd_client, "boot", self.config.device_map()) as cont:
             ccli = cli.Shell(cont.pexpect())
-            ccli.run(f"prepare_turris_image '{os_branch}'", timeout=120)
+            ccli.run(f"prepare_turris_image '{self.config.board}' '{os_branch}'", timeout=120)
             uboot.run("setenv ipaddr 192.168.1.142")
             uboot.run("setenv serverip 192.168.1.1")
             self._board_bootup(uboot)