V4L/DVB (10368): gspca - spca561: Fix bugs and rewrite the init/start of the rev72a.

The bugs were in the first init sequence of the sensor.
The rewrite is adapted from a ms-win trace.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>