"[[" is a bash extension for test. As the ash-implementation is
not fully compatible we drop its usage.
Also change to "=" for simple test, which is sufficient. (see d6ac8ca76c04ed)
Signed-off-by: Sven Roederer <devel-sven@geroedel.de>
[split patch, removed shebang]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>