media: dvb_ringbuffer: Fix typo in dvb_ringbuffer_pkt_write() kerneldoc

There is no such error code EVINAL.

Link: https://lore.kernel.org/linux-media/270f5b7f79a24dc1a3e81d94f6f54fc0f08daf56.1639732105.git.geert+renesas@glider.be


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>