tcg: Clean up local variable shadowing

Fix:

  tcg/tcg.c:2551:27: error: declaration shadows a local variable [-Werror,-Wshadow]
                    MemOp op = get_memop(oi);
                          ^
  tcg/tcg.c:2437:12: note: previous declaration is here
    TCGOp *op;
           ^
  accel/tcg/tb-maint.c:245:18: error: declaration shadows a local variable [-Werror,-Wshadow]
        for (int i = 0; i < V_L2_SIZE; i++) {
                 ^
  accel/tcg/tb-maint.c:210:9: note: previous declaration is here
    int i;
        ^

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20230904161235.84651-2-philmd@linaro.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>