nir/builder: Merge nir_[if]mov_alu into one nir_mov_alu helper

Unless source modifiers are present, fmov and imov are the same.
There's no good reason for having two helpers.

Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

src/compiler/nir/nir_search.c

@@ -669,7 +669,7 @@ nir_replace_instr(nir_builder *build, nir_alu_instr *instr,
     * and rewrite swizzles ourselves.
     */
    nir_ssa_def *ssa_val =
-      nir_imov_alu(build, val, instr->dest.dest.ssa.num_components);
+      nir_mov_alu(build, val, instr->dest.dest.ssa.num_components);
    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(ssa_val));
 
    /* We know this one has no more uses because we just rewrote them all,