media: ti-vpe: cal: Allocate cal_ctx active_fmt array dynamically

To avoid making the cal_ctx structure layoug depend on the size of the
cal_formats array, allocate the active_fmt array dynamically. This
prepares for splitting the driver in multiple files.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>