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/adc/rockchip-saradc.c b/drivers/adc/rockchip-saradc.c
index ed773b9..850142c 100644
--- a/drivers/adc/rockchip-saradc.c
+++ b/drivers/adc/rockchip-saradc.c
@@ -11,6 +11,7 @@
 #include <dm.h>
 #include <errno.h>
 #include <asm/io.h>
+#include <linux/err.h>
 
 #define SARADC_CTRL_CHN_MASK		GENMASK(2, 0)
 #define SARADC_CTRL_POWER_CTRL		BIT(3)