ARM: dts: NSP: Correct RAM amount for BCM958625HR board

The BCM958625HR board has 2GB of RAM available.  Increase the amount
from 512MB to 2GB and add the device type to the memory entry.

Fixes: 9a4865d4

 ("ARM: dts: NSP: Specify RAM amount for BCM958625HR board")
Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>