[media] cx231xx: fix i2c debug prints

Do not shift the already 7bit i2c address.
Print a message also for write+read transactions.
For write+read, print the read buffer correctly instead of using the write
buffer.

Signed-off-by: Matthias Schwarzott <zzam@gentoo.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>