md: Fix static checker warning in analyze_sbs

md: Fix static checker warning in analyze_sbs

The following warn is reported:

 drivers/md/md.c:3912 analyze_sbs()
 warn: iterator 'i' not incremented

Fixes: d8730f0cf4ef ("md: Remove deprecated CONFIG_MD_MULTIPATH")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-raid/7e2e95ce-3740-09d8-a561-af6bfb767f18@huaweicloud.com/T/#t
Signed-off-by: Li Nan <linan122@huawei.com>
Link: https://lore.kernel.org/linux-raid/20251215124412.4015572-1-linan666@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai@fnnas.com>