gpio: tegra: Allow compile test

Allow compile testing this driver by adding a new config option which
is enabled by default and depends on the old symbol or COMPILE_TEST.

Signed-off-by: Alexander Stein <alexanders83@web.de>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 9776ea5..f73f26b 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -400,6 +400,11 @@
 	select GENERIC_IRQ_CHIP
 	select OF_GPIO
 
+config GPIO_TEGRA
+	bool
+	default y
+	depends on ARCH_TEGRA || COMPILE_TEST
+
 config GPIO_TS4800
 	tristate "TS-4800 DIO blocks and compatibles"
 	depends on OF_GPIO