media: cec-pin: improve status log

Keep track of the number of short or long start bits, the number
of short or long data bits and the number of initiated or detected
low drive conditions.

Show this information in the status debugfs log.

Helpful when debugging, particularly when doing error injection
as well.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>