spi/imx: default to m on platforms that have such devices

Acked-by: NJason Wang <jason77.wang@gmail.com>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>

drivers/spi/Kconfig

@@ -147,6 +147,7 @@ config SPI_IMX
 	tristate "Freescale i.MX SPI controllers"
 	depends on ARCH_MXC
 	select SPI_BITBANG
+	default m if IMX_HAVE_PLATFORM_SPI_IMX
 	help
 	  This enables using the Freescale i.MX SPI controllers in master
 	  mode.