arch: re-order the entries in the float choice

Re-order the three entries in the float choice, in a more sensible
order, ie:
- all hard-float options come first, then soft-float
- options that use the FPU are marked so: hard and softfp
- options that do not use the FPU are marked so: software

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

# Compute s390-specific values

CT_DoArchTupleValues() {

    # That's the only thing to override

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

        CT_TARGET_ARCH="s390x"

    fi

}