lima: fix ppir spill stack allocation

lima: fix ppir spill stack allocation

The previous spill stack was fixed and too small, and caused instability
in programs requiring spilling for roughly more than one value.
This patch adds a dynamic calculation of the buffer size based on stack
utilization and switches it to a separate allocation at flush time that
will fit the shader that requires the largest buffer.

Signed-off-by: Erico Nunes <nunes.erico@gmail.com>
Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Reviewed-by: Qiang Yu <yuq825@gmail.com>