media: ti-vpe: cal: fix indexing of cal->ctx[] in cal_probe()

cal->ctx[i] is allocated with this loop
	for (i = 0; i < cal->data->num_csi2_phy; ++i) {
and accessed in the error handler and else where with this loop
	for (i = 0; i < cal->num_contexts; i++)
Because the first loop contains a continue statement
before cal->num_contexts is incremented, using i as the
indexer will leave gaps in the cal->ctx[].

So use cal->num_contexts as the indexer.

Fixes: 75e7e58b ("media: ti-vpe: cal: support 8 DMA contexts")
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>