media: staging: media: zoran: calculate the right buffer number for zoran_reap_stat_com

stable inclusion
from stable-v5.10.110
commit bafec1a6ba4b187a7fcdcfce0faebdc623d4ef8e
bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bafec1a6ba4b187a7fcdcfce0faebdc623d4ef8e



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[ Upstream commit e3b86f4e ]

On the case tmp_dcim=1, the index of buffer is miscalculated.
This generate a NULL pointer dereference later.

So let's fix the calcul and add a check to prevent this to reappear.

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yu Liao <liaoyu15@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>