beagleboard: change to xserver-xorg, not -lite

The difference is less than 16kb, and for that the extra maintenance of two
recipies really isn't worth it.

(From meta-yocto rev: 2ab43f47ae531af5fc850d2aa04f7116ddb1a0e8)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>