[U-Boot] malloc_simple: Allow malloc_simple to be used with non stack RAM

[Hans de Goede]

Hi Tom and Simon,

Here is an old patch of mine, which at the time I
send it got reviewed by Simon, but never got merged.

I've just brushed this patch of, because it shrinks the SPL
by about 3k, and with the spl nand support we've recently
added we are going over the size limit with the SPL on
some sunxi boards.

So I would like to see this merged. Simon, does your ack still
stand for this patch ? Tom, if so can you merge this please ?

Note this patch has close to 0 chance of causing regressions as it
is a nop unless the new CONFIG_SYS_MALLOC_F_BASE define is defined.

Patch 2 / 3 are merely added as example / for Ian to review :)
I will merge these through the sunxi tree once patch 1 is merged.

Thanks & Regards,

Hans