media: gspca/sq905.c: fix uninitialized variable

media: gspca/sq905.c: fix uninitialized variable

BugLink: https://bugs.launchpad.net/bugs/1928825
[ Upstream commit eaaea4681984c79d2b2b160387b297477f0c1aab ]

act_len can be uninitialized if usb_bulk_msg() returns an error.
Set it to 0 to avoid a KMSAN error.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: syzbot+a4e309017a5f3a24c7b3@syzkaller.appspotmail.com
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
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>