bcm63xx: a226m-fwb: fix linux partition offset

bcm63xx: a226m-fwb: fix linux partition offset

The Pirelli A226M-FWB has a wrong linux partition offset, caused
by a copy-paste error. As of result of this, OpenWrt is currently
broken in this unit.

Fix it.

While at it, also use generic node names and fix the addresses
there as well.

Fixes: a27d59bb4274 ("brcm63xx: switch to new partition layout
specification")

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
[also fix/update node names, extend commit message]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>