yam: fix a memory leak in yam_siocdevprivate()

yam: fix a memory leak in yam_siocdevprivate()

BugLink: https://bugs.launchpad.net/bugs/1962345
[ Upstream commit 29eb31542787e1019208a2e1047bb7c76c069536 ]

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

Fixes: 0781168e23a2 ("yam: fix a missing-check bug")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>