kirkwood/goflexhome/goflexnet: merge "root" and unused mtd partitions into one volume "ubi"

The kernel will automatic attach mtd partitions named 'ubi' to ubi0.
Renaming the "root" partition into "ubi" will safe arguments
from the kernel cmdline.

Signed-off-by: Alexander Couzens <lynxis@fe80.eu>

SVN-Revision: 49014