dm: core: Require users of devres to include the header

At present devres.h is included in all files that include dm.h but few
make use of it. Also this pulls in linux/compat which adds several more
headers. Drop the automatic inclusion and require files to include devres
themselves. This provides a good indication of which files use devres.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
index a43793c..08935d9 100644
--- a/drivers/net/phy/dp83867.c
+++ b/drivers/net/phy/dp83867.c
@@ -5,6 +5,7 @@
  */
 #include <common.h>
 #include <phy.h>
+#include <dm/devres.h>
 #include <linux/compat.h>
 #include <malloc.h>