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>

drivers/virtio/virtio_mmio.c

@@ -13,6 +13,7 @@
 #include <virtio.h>
 #include <virtio_ring.h>
 #include <linux/compat.h>
+#include <linux/err.h>
 #include <linux/io.h>
 #include "virtio_mmio.h"
 

drivers/virtio/virtio_pci_legacy.c

@@ -13,6 +13,7 @@
 #include <virtio_ring.h>
 #include <dm/device.h>
 #include <linux/compat.h>
+#include <linux/err.h>
 #include <linux/io.h>
 #include "virtio_pci.h"
 

drivers/virtio/virtio_pci_modern.c

@@ -13,6 +13,7 @@
 #include <virtio_ring.h>
 #include <dm/device.h>
 #include <linux/compat.h>
+#include <linux/err.h>
 #include <linux/io.h>
 #include "virtio_pci.h"
 

drivers/virtio/virtio_sandbox.c

@@ -11,6 +11,7 @@
 #include <virtio.h>
 #include <virtio_ring.h>
 #include <linux/compat.h>
+#include <linux/err.h>
 #include <linux/io.h>
 
 struct virtio_sandbox_priv {