sim: cris: change temp var name slightly to avoid shadowing

Rename the temp var to avoid shadowing another one:

.../sim/cris/semcrisv10f-switch.c:11032:22: error: declaration of ‘tmp_tmpb’ shadows a previous local [-Werror=shadow=compatible-local]
11032 |   tmp_tmpb = ({   SI tmp_tmpb;
      |                      ^~~~~~~~
.../sim/cris/semcrisv10f-switch.c:11031:24: note: shadowed declaration is here
11031 |   tmp_tmpres = ({   SI tmp_tmpb;
      |                        ^~~~~~~~
3 files changed