V4L/DVB (11351): v4l: use usb_interface for v4l2_device_register

If usb_interface.dev is used as dev parameter for v4l2_device_register
v4l2_dev.name contains the v4l driver/module name and usb device and
interface instead of a simple "usb x-y".
It also matches the recommendation to set the parent devices for usb
drivers.
Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/video4linux/v4l2-framework.txt

@@ -90,7 +90,7 @@ up before calling v4l2_device_register then it will be untouched. If dev is
 NULL, then you *must* setup v4l2_dev->name before calling v4l2_device_register.
 
 The first 'dev' argument is normally the struct device pointer of a pci_dev,
-usb_device or platform_device. It is rare for dev to be NULL, but it happens
+usb_interface or platform_device. It is rare for dev to be NULL, but it happens
 with ISA devices or when one device creates multiple PCI devices, thus making
 it impossible to associate v4l2_dev with a particular parent.