usb: gadget: uvc: set nbuffers to minimum STREAMING_MIN_BUFFERS in uvc_queue_setup

We set the minimum amount of v4l2 buffers that is possibly be pending
to UVCG_STREAMING_MIN_BUFFERS which is two. This way the driver will
always have at least one frame pending to be encoded while the other
is being enqueued in the hardware.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20240403-uvc_request_length_by_interval-v7-7-e224bb1035f0@pengutronix.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>