media: i2c: alvium: remove the fr field of the alvium_dev structure

media: i2c: alvium: remove the fr field of the alvium_dev structure

The fr (frame rate) field of the alvium_dev structure is
only used to pass result from alvium_set_frame_interval() to
alvium_set_frame_rate() that writes this info into the hw reg.
Replace it with a function parameter.

Signed-off-by: Tommaso Merciai <tomm.merciai@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>