MIPS: BCM47xx: Really fix 128MB RAM problem

MIPS: BCM47xx: Really fix 128MB RAM problem

The previous patch 4a86f2d27733f610e642649aca3e82e86fca9e22 (lmo) rsp.
84a6fcb368a080620d12fc4d79e07902dbee7335 (kernel.org) was wrong.

The BCM47xx architecture maps the ram into a 128MB address space. It
will be spaced there as often as goes into the 128MB. Detection tries to
find the position where the same memory is found. When reading beyond
128MB the processor will throw an exception. If 128MB RAM is installed,
it will not find a memory alias because it tries to read beyond the 128MB
border. Now it just assumes 128MB installed ram if it can not find an
alias.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1508/
Acked-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>