control_ids.h defines the contrast type as float, let's use the same in simple IPA, instead of double. Saturation and gamma already use float, except for the knobs initializers, let's use float for the knobs too. Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com> Reviewed-by: Robert Mader <robert.mader@collabora.com> Signed-off-by: Milan Zamazal <mzamazal@redhat.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>