MIPS: lantiq: Set physical_memsize

physical_memsize is needed by the vpe loader code and the platform
specific code has to define it. This value will be given to the
firmware loaded with the VPE loader. I am not aware of any standard
interface or better value to provide here.

Reported-by: kbuild test robot <lkp@intel.com>
Fixes: d9ae4f18 ("MIPS: Lantiq: Activate more drivers in default configuration")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: John Crispin <john@phrozen.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14908/


Signed-off-by: James Hogan <james.hogan@imgtec.com>