V4L/DVB (4086): There were a cross-reference on cpia and cpia_pp/cpia_usb

Those cross-references were generating an error:
*** Warning: "cpia_pp_init" [/home/v4l/master/v4l/cpia.ko] undefined!
*** Warning: "cpia_usb/_init" [/home/v4l/master/v4l/cpia.ko] undefined!

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>