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/cadence_qspi.c b/drivers/spi/cadence_qspi.c
index f8b6940..0b503dd 100644
--- a/drivers/spi/cadence_qspi.c
+++ b/drivers/spi/cadence_qspi.c
@@ -13,6 +13,7 @@
 #include <reset.h>
 #include <spi.h>
 #include <spi-mem.h>
+#include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/sizes.h>
 #include "cadence_qspi.h"