MIPS: generic/yamon-dt: Support > 256MB of RAM

MIPS: generic/yamon-dt: Support > 256MB of RAM

YAMON can expose more than 256MB of RAM to Linux on Malta by passing an
ememsize environment variable with the full size, but the kernel then
needs to be careful to choose the corresponding physical memory regions,
avoiding the IO memory window. This is platform dependent, and on Malta
it also depends on the memory layout which varies between system
controllers.

Extend yamon_dt_amend_memory() to generically handle this by taking
[e]memsize bytes of memory from an array of memory regions passed in as
a new parameter. Board code provides this array as appropriate depending
on its own memory map.

[paul.burton@imgtec.com: SEAD-3 supports 384MB DDR from 0]

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16182/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>