MIPS: Netlogic: Read memory from DRAM BARs

Read the memory from the Bridge DRAM BARs, if it is not passed in
from the device tree. This will allow us to remove memory configuration
from built in device trees.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5743/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>