libfdt: Handle v16 and re-ordered trees for r/w

[Jon Loeliger]

So, like, the other day David Gibson mumbled:
> Currently all the read/write functions in libfdt require that the
> given tree be v17, and further, that the tree has the memory
> reservation block, structure block and strings block stored in that
> physical order.
> 
> This patch eases these constraints, by making fdt_open_int() reorder
> the blocks, and/or convert the tree to v17, so that it will then be
> ready for the other read-write functions.
> 
> It also extends fdt_pack() to actually remove any gaps between blocks
> that might be present.
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Applied.

jdl