All these instructions replicate the result of a N-component dot-product
to a vec4.  Naming them fdot_replicatedN gives the impression that are
some sort of abstract dot-product that replicates the result to a vecN.
They also deviate from fdph_replicated... which nobody would reasonably
consider naming fdot_replicatedh.

Naming these opcodes fdotN_replicated more closely matches what they
are, and it matches the pattern of fdph_replicated.

I believe that the only reason these opcodes were named this way was
because it simplified the implementation of the binop_reduce function in
nir_opcodes.py.  I made some fairly simple changes to that function, and
I think the end result is ok.

The bulk of the changes come from the sed rename:

    sed --in-place -e 's/fdot_replicated\([234]\)/fdot\1_replicated/g' \
        $(grep -r 'fdot_replicated[234]' src/)

v2: Use a named parameter to binop_reduce instead of using
isinstance(name, str).  Suggested by Jason.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <!5725>