ARM: OMAP: Add CONFIG_OMAP_COMMON

Adding a new CONFIG_OMAP_COMMON which is included by all boards
that needs to build cpu/armv7/omap-common folder.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
diff --git a/include/configs/dig297.h b/include/configs/dig297.h
index bf91625..30e3908 100644
--- a/include/configs/dig297.h
+++ b/include/configs/dig297.h
@@ -30,6 +30,7 @@
 #define CONFIG_OMAP		/* in a TI OMAP core */
 #define CONFIG_OMAP34XX		/* which is a 34XX */
 #define CONFIG_OMAP_GPIO
+#define CONFIG_OMAP_COMMON
 
 #define CONFIG_SYS_TEXT_BASE	0x80008000