drm/tegra: dc: Clarify comment about cursor treatment

		return ERR_PTR(-ENOMEM);

	/*

	 * We'll treat the cursor as an overlay plane with index 6 here so

	 * that the update and activation request bits in DC_CMD_STATE_CONTROL

	 * match up.

	 * This index is kind of fake. The cursor isn't a regular plane, but

	 * its update and activation request bits in DC_CMD_STATE_CONTROL do

	 * use the same programming. Setting this fake index here allows the

	 * code in tegra_add_plane_state() to do the right thing without the

	 * need to special-casing the cursor plane.

	 */

	plane->index = 6;