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/block/blk-uclass.c b/drivers/block/blk-uclass.c
index ca8978f..7771114 100644
--- a/drivers/block/blk-uclass.c
+++ b/drivers/block/blk-uclass.c
@@ -10,6 +10,7 @@
 #include <dm/device-internal.h>
 #include <dm/lists.h>
 #include <dm/uclass-internal.h>
+#include <linux/err.h>
 
 static const char *if_typename_str[IF_TYPE_COUNT] = {
 	[IF_TYPE_IDE]		= "ide",