media: staging: media: usbvision: usbvision-core Correct spelling

Correct spelling in comment

Signed-off-by: John Oldman <john.oldman@polehill.co.uk>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>