Enforce use of bind mount for /dev within chroot

The /dev/mapper directory created by devtmpfs lacked entry for
armbian-root thereby breaking the cryptsetup configuration generated
within initrd file. Use bind mount as that doesn't seem to suffer from
that issue.

lib/functions/general/chroot-helpers.sh

@@ -24,7 +24,7 @@ function mount_chroot() {
 	mount -t tmpfs -o "size=99%" tmpfs "${target}/run/user/0"
 	mount -t proc chproc "${target}"/proc
 	mount -t sysfs chsys "${target}"/sys
-	mount -t devtmpfs chdev "${target}"/dev || mount --bind /dev "${target}"/dev
+	mount --bind /dev "${target}"/dev
 	mount -t devpts chpts "${target}"/dev/pts || mount --bind /dev/pts "${target}"/dev/pts
 }