dtc: Make helper macros in trees.S more flexible

[Jon Loeliger]

So, like, the other day David Gibson mumbled:
> This patch makes the helper macros in trees.S use separate labels for
> the end of each dt subblock, rather than using only start labels.
> This means that the macros can now be used to create trees with the
> subblocks in non-standard orders.
> 
> In addition, it adds a bunch of extra ; after lines of asm code in
> macros, making them safe to use in nested macros.
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Applied.

jdl