V4L/DVB (6627): CXUSB: handle write then read from different address

The path to perform a read immediately after a write was not checking that
the address being read from was the same as the one that was written.

Handling this case correctly should mean that we now can handle more than
two i2c messages at a time.

Signed-off-by: Chris Pascoe <c.pascoe@itee.uq.edu.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>