target/loongarch: Clean up tlb when cpu reset

We should make sure that tlb is clean when cpu reset.

Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20220705070950.2364243-1-gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>