media: pulse8-cec: reorganize function order

Reorganize the order of the functions in the source, going from
low-level to high-level.

No functional changes were made.

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