lima/ppir: duplicate consts in nir
Move the duplicate consts step to a nir pass.
This makes the nir representation closer to what ppir will have in the
result.
Additionally, it handles the case where a const is used multiple times
by a single node (which can happen in instructions like fcsel). The new
implementation will only emit a single load const for that case.
Signed-off-by: Erico Nunes <nunes.erico@gmail.com>
Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4535>