kconfig: remove duplicated CMD_DNS option
two CMD_DNS options were added by commit 60296a835cb17 ("commands: add more
command entries in Kconfig")
Signed-off-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Andrey Skvortsov