nir: Drop bogus nir_var_shader_in case in nir_lower_io's store_op().

This can't happen, the caller asserts that mode is shader_out or shared.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/compiler/nir/nir_lower_io.c

@@ -198,7 +198,6 @@ store_op(struct lower_io_state *state,
 {
    nir_intrinsic_op op;
    switch (mode) {
-   case nir_var_shader_in:
    case nir_var_shader_out:
       op = per_vertex ? nir_intrinsic_store_per_vertex_output :
                         nir_intrinsic_store_output;