media: i2c: imx214: Use subdev active state

Port the imx214 sensor driver to use the subdev active state.

Move all the format configuration to the subdevice state and simplify
the format handling, locking and initialization.

While at it, simplify imx214_start_streaming() by removing unneeded goto
statements and the corresponding error label.

Signed-off-by: André Apitzsch <git@apitzsch.eu>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>