spi: Kconfig: Add TEGRA20_SFLASH entry

Added TEGRA20_SFLASH entry on Kconfig with help description.

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

drivers/spi/Kconfig

@@ -93,6 +93,13 @@ config TEGRA114_SPI
 	  This controller is different than the older SoCs SPI controller and
 	  also register interface get changed with this controller.
 
+config TEGRA20_SFLASH
+	bool "nVidia Tegra20 Serial Flash controller driver"
+	help
+	  Enable the nVidia Tegra20 Serial Flash controller driver. This driver
+	  can be used to access the SPI NOR flash on platforms embedding this
+	  nVidia Tegra20 IP core.
+
 config XILINX_SPI
 	bool "Xilinx SPI driver"
 	help