ARM: dts: BCM5301X: Specify all RAM by including an extra block

The first 128 MiB of RAM can be accessed using an alias at address 0x0.

In theory we could access whole RAM using 0x80000000 - 0xbfffffff range
(up to 1 GiB) but it doesn't seem to work on Northstar. For some reason
(hardware setup left by the bootloader maybe?) 0x80000000 - 0x87ffffff
range can't be used. I reproduced this problem on:
1) Buffalo WZR-600DHP2 (BCM47081)
2) Netgear R6250 (BCM4708)
3) D-Link DIR-885L (BCM47094)

So it seems we're forced to access first 128 MiB using alias at 0x0 and
the rest using real base address + 128 MiB offset which is 0x88000000.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>