nir: Don't print swizzles when there are more than 4 components

... as can happen with various types like mat4, or else we'll smash the
stack writing past the end of components_local[].

Fixes: 5a0d3e1129b7 ("nir: Print the components referenced for split or
                      packed shader in/outs.")
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
1 file changed