[ARM] tegra: add GPIO support

v2: fixes from Mike Rapoport:
	- move gpio-names.h to arch/arm/mach-tegra
    fixes from Russell King
	- include linux/io.h and linux/gpio.h instead of asm/io.h
	  and asm/gpio.h
    additional changes:
    	- add macros to convert between irq and gpio numbers for platform data
	- change for_each_bit to for_each_set_bit in gpio.c
v3:
	- minor bugfixes

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Erik Gilling <konkers@android.com>
diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index bcbda96..a57713c 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -9,6 +9,7 @@
 	bool "Tegra 2 family"
 	select CPU_V7
 	select ARM_GIC
+	select ARCH_REQUIRE_GPIOLIB
 	help
 	  Support for NVIDIA Tegra AP20 and T20 processors, based on the
 	  ARM CortexA9MP CPU and the ARM PL310 L2 cache controller