MIPS: Malta: Detect and fix bad memsize values

memsize denotes the amount of RAM we can access from kseg{0,1} and
that should be up to 256M. In case the bootloader reports a value
higher than that (perhaps reporting all the available RAM) it's best
if we fix it ourselves and just warn the user about that. This is
usually a problem with the bootloader and/or its environment.

[ralf@linux-mips.org: Remove useless parens as suggested bei Sergei.
Reformat long pr_warn statement to fit into 80 column limit.]

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # v3.15+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9362/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>