net: marvell: prestera: fix incorrect return of port_find

stable inclusion
from stable-v5.10.89
commit 78e49d77e517c205e7c2c2f7a970468dd2f867b1
bugzilla: 186140 https://gitee.com/openeuler/kernel/issues/I4S8HA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=78e49d77e517c205e7c2c2f7a970468dd2f867b1



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[ Upstream commit 8b681bd7 ]

In case, when some ports is in list and we don't find requested - we
return last iterator state and not return NULL as expected.

Fixes: 501ef306 ("net: marvell: prestera: Add driver for Prestera family ASIC devices")
Signed-off-by: Yevhen Orlov <yevhen.orlov@plvision.eu>
Link: https://lore.kernel.org/r/20211216170736.8851-1-yevhen.orlov@plvision.eu


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>