linux-imx

init/Kconfig: Use short unix-style option instead of --longname

Avoids warning messages with the latest release of toybox, which never
bothered to implement the --longopts nothing was using.

Signed-off-by: Rob Landley <rob@landley.net>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>