scripts: prevent trailing - in CT_TARGET

Not all target tuples consist of an VENDOR, KERNEL and SYSTEM part, build up the
tuple in such a way to no extra or trailing dashes are added to CT_TARGET

Signed-off-by: Bart vdr Meulen <bartvdrmeulen@gmail.com>

# m68k specific configuration file

# depends on EXPERIMENTAL

config ARCH_m68k

    select ARCH_SUPPORTS_32

    select ARCH_DEFAULT_32

    select ARCH_DEFAULT_BE

    select ARCH_SUPPORT_CPU

     help

      The m68k architecture