Added bufferless operation to the video capture example. Can be tested with e.g. nanoCH32V305 board with the following settings:

- tusb_config.h
  - #define CFG_TUD_VIDEO_STREAMING_EP_BUFSIZE  1024
  - #define CFG_TUD_VIDEO_STREAMING_BULK 1
  - #define CFG_EXAMPLE_VIDEO_DISABLE_MJPEG
  - #define CFG_EXAMPLE_VIDEO_BUFFERLESS

and

- usb_descriptor.h
  - #define FRAME_RATE    60