media: i2c: imx214: Prepare for variable clock frequency

Move clock frequency related parameters out of the constant register
sequences, such that the hard coded external clock frequency can be
replaced by a variable in the upcoming patches.

Acked-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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>