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/spi/spi-mem.c b/drivers/spi/spi-mem.c
index cc358bd..b8cf8dd 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -7,6 +7,7 @@
  */
 
 #ifndef __UBOOT__
+#include <dm/devres.h>
 #include <linux/dmaengine.h>
 #include <linux/pm_runtime.h>
 #include "internals.h"