media: ti-vpe: cal: rename non-MC funcs to cal_legacy_*

To make it more obvious if the function in question is dealing with
media-controller API or the legacy API, rename legacy API functions to
cal_legacy_*.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>