V4L/DVB (6857): cx23885: correctly join I2C writes and reads from same address

When an I2C message specifies a write then a read from the same I2C address,
we need to tell the chip to not release the bus between the message parts.

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