OMAP: omap_device: add to_omap_device() macro

Following the model of to_platform_device(), add to_omap_device()
macro so a platform_device pointer can be converted into an
omap_device pointer.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
diff --git a/arch/arm/plat-omap/include/plat/omap_device.h b/arch/arm/plat-omap/include/plat/omap_device.h
index 11a9773..d939246 100644
--- a/arch/arm/plat-omap/include/plat/omap_device.h
+++ b/arch/arm/plat-omap/include/plat/omap_device.h
@@ -137,5 +137,7 @@
 };
 
 
-#endif
+/* Get omap_device pointer from platform_device pointer */
+#define to_omap_device(x) container_of((x), struct omap_device, pdev)
 
+#endif