V4L/DVB (11035): mt9t031 bugfix

- The video device is not allocated when mt9t031_init() is called, don't use
it in debug printk.

- The clock polarity is inverted in mt9t031_set_bus_param(), use the correct
one.

Signed-off-by: Philippe Rétornaz <philippe.retornaz@epfl.ch>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>