kernel/linux: change m68k/no-mmu linux arch tuple to use -uclinux

GCC requires m68k arch tuples to be *-*-uclinux-* to support Linux on
no-mmu m68k (ColdFire) cpus.

Blackfin arch tuple must be *-*-linux-uclibc for FD_PIC_ELF toolchains,
so we cannot just switch to uclinux for no-mmu Linux toolchains.

Signed-off-by: "Esben Haabendal" <esben@haabendal.dk>
Message-Id: <876271s1ee.fsf@arh128.prevas.dk>
PatchWork-Id: 186976

 # Compute sparc-specific values

 CT_DoArchTupleValues() {

     # That's the only thing to override

     if [ "${CT_ARCH_64}" = "y" ]; then

         CT_TARGET_ARCH="${CT_ARCH}64"

     fi

 }