media: input: serio.h: add SERIO_EXTRON_DA_HD_PLUS

Add a new serio ID for the Extron DA HD 4K Plus series of 4K HDMI
Distribution Amplifiers. These devices support CEC over the serial
port, so a new serio ID is needed to be able to associate the CEC
driver.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>