ARM: chiliboard: enable DM_SPI

Add DM_SPI to suppress build warning about dm conversion.

Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
diff --git a/configs/chiliboard_defconfig b/configs/chiliboard_defconfig
index 02eb324..ceba006 100644
--- a/configs/chiliboard_defconfig
+++ b/configs/chiliboard_defconfig
@@ -42,6 +42,7 @@
 CONFIG_MII=y
 CONFIG_DRIVER_TI_CPSW=y
 CONFIG_SPI=y
+CONFIG_DM_SPI=y
 CONFIG_OMAP3_SPI=y
 CONFIG_TIMER=y
 CONFIG_OMAP_TIMER=y