intel/vec4: Also use MOV_FOR_SCRATCH for swizzle resolves

In 2db8867943, we introduced a new meta-op MOV_FOR_SCRATCH which is
identical to MOV except it lets us identify MOVs emitted during spilling
so we know not to re-spill those instructions.  We emit them from
shuffle_for_64bit_data whenever the new for_scratch parameter is true.
Unfortunately, we missed the one used for resolving swizzles.

Fixes: 2db8867943 "intel/vec4: Don't spill fp64 registers more..."
Tested-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11155>

src/intel/compiler/brw_vec4_nir.cpp

@@ -2177,7 +2177,7 @@ vec4_visitor::shuffle_64bit_data(dst_reg dst, src_reg src, bool for_write,
    /* Resolve swizzle in src */
    if (src.swizzle != BRW_SWIZZLE_XYZW) {
       dst_reg data = dst_reg(this, glsl_type::dvec4_type);
-      bld.MOV(data, src);
+      bld.emit(mov_op, data, src);
       src = src_reg(data);
    }