media: ttusb-dec: fix memory leak in ttusb_dec_exit_dvb()

stable inclusion
from stable-v4.19.285
commit 3e5af0745a4702ab0df2f880bfe0431eb30f9164
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I635HP
CVE: CVE-2022-45887

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.19.y&id=3e5af0745a4702ab0df2f880bfe0431eb30f9164

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[ Upstream commit 517a2813 ]

Since dvb_frontend_detach() is not called in ttusb_dec_exit_dvb(),
which is called when the device is disconnected, dvb_frontend_free()
is not finally called.

This causes a memory leak just by repeatedly plugging and
unplugging the device.

Fix this issue by adding dvb_frontend_detach() to ttusb_dec_exit_dvb().

Link: https://lore.kernel.org/linux-media/20221117045925.14297-5-imv4bel@gmail.com


Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>