Add a new s_config core ops call: this is called with the irq and platform
data to be used to initialize the subdev.

Added new v4l2_i2c_new_subdev_cfg and v4l2_i2c_new_subdev_board calls
that allows you to pass these new arguments.

The existing v4l2_i2c_new_subdev functions were modified to also call
s_config.

In the future the existing v4l2_i2c_new_subdev functions will be replaced
by a single v4l2_i2c_new_subdev function similar to v4l2_i2c_new_subdev_cfg
but without the irq and platform_data arguments.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>