brcm63xx: add Livebox 1 firmware image generation

Currently there isn't images ready for flashing liveboxes boards. This
patch adds a script and the code to call it in the  bcm63xx images
builder makefile to generate the livebox 1 firmware.

I removed some lines to avoid generating unneded files in the bin/ dir
for this board. And added code to generate a squashed rootfs aligned to
64 kB since the current one in the /bin dir is 128 kB aligned and
doesn't work. Still no sysupgrade support for this board. Upgrading from
within openwrt can be done writing with mtd the kernel, and then the 64k
aligned rootfs.

Regards

Signed-off-by: Daniel Gonzalez <dgcbueu@gmail.com>
[jogo: use sed instead of a separate shell script for the boot script, make it
 respect the load address]
Signed-off-by: Jonas Gorski <jogo@openwrt.org>

SVN-Revision: 44982