lantiq: install uboot-envtools by default on BTHOMEHUBV3A

The only way to access the u-boot console on the BTHOMEHUBV3A
is by soldering a serial console onto some really tiny pads.

To enable installation without soldering it would be helpful
to be able to modify the uboot environment from within
the ramdisk image used as part of the installation process.

Signed-off-by: Ben Mulvihill <ben.mulvihill@gmail.com>

SVN-Revision: 49253