media: ti: cal: fix possible memory leak in cal_ctx_create()

The memory of ctx is allocated in cal_ctx_create(), but it will
not be freed when cal_ctx_v4l2_init() fails, so add kfree() when
cal_ctx_v4l2_init() fails to fix it.

Fixes: d68a94e9 ("media: ti-vpe: cal: Split video device initialization and registration")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>