script: allow to pass any float value for CT_LOAD

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Message-Id: <b51acf21c72b4a8e882e.1359320015@laptop>
Patchwork-Id: 216062

 reporter_name="Remy Bohmer"

 reporter_url="linux@bohmer.net"

 reporter_comment="Example for building a toolchain for m68000 bare metal targets"