nir: Add missing break into switch in construct_value()

There seemed to be missing one break in nested switchcases.

Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Reviewed-by: Antia Puentes <apuentes@igalia.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/compiler/nir/nir_search.c

@@ -521,6 +521,7 @@ construct_value(const nir_search_value *value,
          default:
             unreachable("unknown bit size");
          }
+         break;
 
       case nir_type_bool32:
          load->value.u32[0] = c->data.u;