tegra: Add SOC support for display/lcd

Add support for the LCD peripheral at the Tegra2 SOC level. A separate
LCD driver will use this functionality to configure the display.

Signed-off-by: Mayuresh Kulkarni <mkulkarni@nvidia.com>
Mayuresh Kulkarni:
- changes to remove bitfields and clean up for submission

Signed-off-by: Simon Glass <sjg@chromium.org>
Simon Glass:
- simplify code, move clock control into here, clean-up
Signed-off-by: Tom Warren <twarren@nvidia.com>

include/fdtdec.h

@@ -67,6 +67,7 @@ enum fdt_compat_id {
 	COMPAT_NVIDIA_TEGRA20_KBC,	/* Tegra20 Keyboard */
 	COMPAT_NVIDIA_TEGRA20_NAND,	/* Tegra2 NAND controller */
 	COMPAT_NVIDIA_TEGRA20_PWM,	/* Tegra 2 PWM controller */
+	COMPAT_NVIDIA_TEGRA20_DC,	/* Tegra 2 Display controller */
 
 	COMPAT_COUNT,
 };