media: fdp1: Fix R-Car M3-N naming in debug message

The official name is "R-Car M3-N", not "R-Car M3N".

Fixes: 4e8c120d ("media: fdp1: Support M3N and E3 platforms")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>