video: move tegra dc driver into own folder

Move tegra dc driver to tegra20 directory and also mention
T30 in description of the driver's config option.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
[agust: add commit description]
Signed-off-by: Anatolij Gustschin <agust@denx.de>
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index cb3f373..4d75771 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -67,10 +67,10 @@
 obj-$(CONFIG_VIDEO_DSI_HOST_SANDBOX) += sandbox_dsi_host.o
 obj-$(CONFIG_VIDEO_SANDBOX_SDL) += sandbox_sdl.o
 obj-$(CONFIG_VIDEO_SIMPLE) += simplefb.o
-obj-$(CONFIG_VIDEO_TEGRA20) += tegra.o
 obj-$(CONFIG_VIDEO_VESA) += vesa.o
 obj-$(CONFIG_VIDEO_SEPS525) += seps525.o
 obj-$(CONFIG_VIDEO_ZYNQMP_DPSUB) += zynqmp_dpsub.o
 
 obj-y += bridge/
 obj-y += sunxi/
+obj-y += tegra20/