lima/ppir: add write after read deps for registers

lima/ppir: add write after read deps for registers

For cases like:

(1) r1 = r2
(2) r2 = ssa1

We need to add (1) as dependency of (2), otherwise scheduler may
reorder them.

Tested-by: Andreas Baierl <ichgeh@imkreisrum.de>
Reviewed-by: Qiang Yu <yuq825@gmail.com>
Reviewed-by: Erico Nunes <nunes.erico@gmail.com>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>