ARM: tegra: add core Tegra186 support

This adds the bare minimum code to support Tegra186, with UART and eMMC
working.

The empty gpio.h is required because <asm/gpio.h> includes it. A future
cleanup round may be able to solve this for all Tegra generations at once.

mach-tegra/Makefile is adjusted not to compile anything for Tegra186, but
instead to defer everything to mach-tegra/tegra186/Makefile. This allows
the SoC code to pick-and-choose which of the C files in the "common"
mach-tegra/ directory to compile in based on the SoC's needs. Most of the
code is not valid for Tegra186, and this approach removes the need for
mach-tegra/Makefile to contain many SoC-specific ifdefs. This approach
may be applied to all other Tegra SoCs in a future cleanup round.

board186.c is introduced to replace board.c and board2.c. These files
currently contain a slew of SoC- and board-specific code that is not
valid for Tegra186. This approach avoids adding yet more ifdefs to those
files. A future cleanup round may refactor most of board*.c into board-/
SoC-specific functions files thus allowing the top-level functions like
board_init_early_f to be shared again.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/include/asm/arch-tegra186/gpio.h

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#ifndef _TEGRA186_GPIO_H_
+#define _TEGRA186_GPIO_H_
+
+#endif

arch/arm/include/asm/arch-tegra186/tegra.h

@@ -0,0 +1,16 @@
+/*
+ * (C) Copyright 2013-2016, NVIDIA CORPORATION.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#ifndef _TEGRA186_TEGRA_H_
+#define _TEGRA186_TEGRA_H_
+
+#define GICD_BASE		0x03881000	/* Generic Int Cntrlr Distrib */
+#define GICC_BASE		0x03882000	/* Generic Int Cntrlr CPU I/F */
+#define NV_PA_SDRAM_BASE	0x80000000
+
+#include <asm/arch-tegra/tegra.h>
+
+#endif