tegra: don't hard-code LCD into default TEGRA_DEVICE_SETTINGS

Only add "lcd" into TEGRA_DEVICE_SETTINGS if CONFIG_VIDEO_TEGRA.
Otherwise, "lcd" is meaningless.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>