media: ti-vpe: cal: fix ctx uninitialization

Somewhere along the way the context uninitialization has gone a bit odd:

* We have cal_ctx_create() but no matching destroy call, but we still
need to call cal_ctx_v4l2_cleanup() for each context.

* We have cal_media_cleanup() which calls cal_ctx_v4l2_cleanup() for all
contexts, but cal_media_init() is not where the contexts are created.

* The order of uninit steps in cal_remove() is different than the error
handling path in cal_probe().

* cal_probe()'s error handling calls cal_ctx_v4l2_cleanup() for each
context, but also calls cal_media_clean(), doing the same context
cleanup twice.

So fix these, by introducing cal_ctx_destroy(), and using that in
appropriate places instead of calling cal_ctx_v4l2_cleanup() in
cal_media_clean(). Also use normal kzalloc (and kfree) instead of devm
version as we anyway do manual cleanup for each context.

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>