tegra2: Plumb in SPI/UART switch code

On Seaboard the UART and SPI interfere with each other. This causes the UART
to receive spurious zero bytes after SPI transactions and also means that
SPI can corrupt a few output characters when it starts up if they are still
in the UART buffer.

This updates the board to use the SPI/UART switch to avoid the problem.

For now this feature is turned off since it needs changes to the NS16550
UART to operate.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/board/nvidia/common/board.c b/board/nvidia/common/board.c
index 6a1312c..c3f6796 100644
--- a/board/nvidia/common/board.c
+++ b/board/nvidia/common/board.c
@@ -112,9 +112,13 @@
  */
 int board_init(void)
 {
+	/* Do clocks and UART first so that printf() works */
 	clock_init();
 	clock_verify();
 
+#ifdef CONFIG_SPI_UART_SWITCH
+	gpio_config_uart();
+#endif
 #ifdef CONFIG_TEGRA2_SPI
 	spi_init();
 #endif
@@ -152,7 +156,11 @@
 	pin_mux_uart(uart_ids);
 
 	/* Initialize periph GPIOs */
+#ifdef CONFIG_SPI_UART_SWITCH
+	gpio_early_init_uart();
+#else
 	gpio_config_uart();
+#endif
 	return 0;
 }
 #endif	/* EARLY_INIT */