DM: SPI: Convert display5 to use SPI with DM/DTS (but no in SPL)

The DM/DTS support for SPI is disabled on purpose for SPL, as it is not
supported as of time of this conversion.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
diff --git a/arch/arm/mach-imx/mx6/Kconfig b/arch/arm/mach-imx/mx6/Kconfig
index 032fd56..7e5a667 100644
--- a/arch/arm/mach-imx/mx6/Kconfig
+++ b/arch/arm/mach-imx/mx6/Kconfig
@@ -200,6 +200,7 @@
 	select DM_ETH
 	select DM_I2C
 	select DM_MMC
+	select DM_SPI
 	select DM_GPIO
 	select DM_SERIAL
 	select SUPPORT_SPL