lima/ppir: lower fdot in nir_opt_algebraic

lima/ppir: lower fdot in nir_opt_algebraic

Now that we have fsum in nir, we can move fdot lowering there.
This helps reduce ppir complexity and enables the lowered ops to be part
of other nir optimizations in the optimization loop.

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