distro-agnostic: dropbear-initramfs: make sure directory exists [cherry-pick]

lib/functions/rootfs/distro-agnostic.sh

@@ -40,6 +40,11 @@ function install_distribution_agnostic() {
 			# generate a default ssh key for login on dropbear in initramfs
 			# this key should be changed by the user on first login
 			display_alert "Generating a new SSH key pair for dropbear (initramfs)" "" ""
+
+			# Make sure that the relevant directory exists
+			[[ -d "${SDCARD}"/etc/dropbear-initramfs ]] || mkdir "${SDCARD}"/etc/dropbear-initramfs
+
+			# Generate the SSH keys
 			ssh-keygen -t ecdsa -f "${SDCARD}"/etc/dropbear-initramfs/id_ecdsa \
 				-N '' -O force-command=cryptroot-unlock -C 'AUTOGENERATED_BY_ARMBIAN_BUILD' 2>&1