media: cec-notifier: rename conn_name to port_name

This argument refers to a stable name for an HDMI port, mostly i915
(ACPI) specific. Since we'll be introducing a more generic 'name' argument
as well later, rename this now to avoid confusion.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>