spi/imx: Drop default setting for SPI_IMX

SPI_IMX is selected by imx_v6_v7_defconfig/imx_v4_v5_defconfig and we don't need
to have a default setting which depends on the IMX_HAVE_PLATFORM_SPI_IMX symbol.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NMark Brown <broonie@linaro.org>

drivers/spi/Kconfig

@@ -212,7 +212,6 @@ config SPI_IMX
 	tristate "Freescale i.MX SPI controllers"
 	depends on ARCH_MXC || COMPILE_TEST
 	select SPI_BITBANG
-	default m if IMX_HAVE_PLATFORM_SPI_IMX
 	help
 	  This enables using the Freescale i.MX SPI controllers in master
 	  mode.