There is no input check when echo md/max_read_errors and overflow might
occur. Add check of input number.

Fixes: 1e50915f ("raid: improve MD/raid10 handling of correctable read errors.")
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230522072535.1523740-3-linan666@huaweicloud.com