tegra: Add tegra_get_chip_type() to detect SKU

We want to know which type of chip we are running on - the Tegra
family has several SKUs. This can be determined by reading a
fuse register, so add this function to ap20.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/arch/arm/include/asm/arch-tegra2/ap20.h b/arch/arm/include/asm/arch-tegra2/ap20.h
index a4b4d73..d222c44 100644
--- a/arch/arm/include/asm/arch-tegra2/ap20.h
+++ b/arch/arm/include/asm/arch-tegra2/ap20.h
@@ -100,3 +100,10 @@
 
 /* This is the main entry into U-Boot, used by the Cortex-A9 */
 extern void _start(void);
+
+/**
+ * Works out the SOC type used for clocks settings
+ *
+ * @return	SOC type - see TEGRA_SOC...
+ */
+int tegra_get_chip_type(void);