yam: fix a memory leak in yam_siocdevprivate()

mainline inclusion
from mainline-v5.17-rc2
commit 29eb3154
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4U4NY


CVE: CVE-2022-24959

-------------------------------------------------

ym needs to be free when ym->cmd != SIOCYAMSMCS.

Fixes: 0781168e ("yam: fix a missing-check bug")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

conflict:
	The bug is in function yam_siocdevprivate() in mainline,
but it is in function yam_ioctl() because the function name is
changed in 25ec92fb("hamradio: use ndo_siocdevprivate") in
mainline.

Signed-off-by: Lu Wei <luwei32@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>