media: nvidia: tegra-vde: Replace file->private_data access

media: nvidia: tegra-vde: Replace file->private_data access

Accessing file->private_data manually to retrieve the v4l2_fh pointer is
error-prone, as the field is a void * and will happily cast implicitly
to any pointer type.

The tegra-vde driver accesses file->private_data in the tegra_open()
function, right after setting the field to &ctx->fh. Replace the
accesses with usage of &ctx->fh.

No functional change is intended, this only paves the way to remove
direct accesses to file->private_data and make V4L2 drivers safer.
Other accesses to the field will be addressed separately.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>