spi: fsl-(e)spi: Support compile as module

Signed-off-by: Esben Haabendal <eha@deif.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 9982998..468d13c 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -279,7 +279,7 @@
 	depends on FSL_SOC
 
 config SPI_FSL_SPI
-	bool "Freescale SPI controller and Aeroflex Gaisler GRLIB SPI controller"
+	tristate "Freescale SPI controller and Aeroflex Gaisler GRLIB SPI controller"
 	depends on OF
 	select SPI_FSL_LIB
 	select SPI_FSL_CPM if FSL_SOC
@@ -300,7 +300,7 @@
 	  mode. VF610 platform uses the controller.
 
 config SPI_FSL_ESPI
-	bool "Freescale eSPI controller"
+	tristate "Freescale eSPI controller"
 	depends on FSL_SOC
 	select SPI_FSL_LIB
 	help