apalis/colibri_t30: add note about colibri vs. nvidia uart mapping

The following mapping is applicable for Apalis T30:

Apalis UART1: NVIDIA UARTA
Apalis UART2: NVIDIA UARTD
Apalis UART3: NVIDIA UARTB
Apalis UART4: NVIDIA UARTC

The following mapping is applicable for Colibri T30:

Colibri UART-A: NVIDIA UARTA
Colibri UART-B: NVIDIA UARTD
Colibri UART-C: NVIDIA UARTB

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/include/configs/colibri_t30.h b/include/configs/colibri_t30.h
index fa0fa93..94802a6 100644
--- a/include/configs/colibri_t30.h
+++ b/include/configs/colibri_t30.h
@@ -14,7 +14,13 @@
 
 /* High-level configuration options */
 
-/* Board-specific serial config */
+/*
+ * Board-specific serial config
+ *
+ * Colibri UART-A: NVIDIA UARTA
+ * Colibri UART-B: NVIDIA UARTD
+ * Colibri UART-C: NVIDIA UARTB
+ */
 #define CONFIG_TEGRA_ENABLE_UARTA
 #define CONFIG_SYS_NS16550_COM1		NV_PA_APB_UARTA_BASE