common: Drop linux/delay.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/regmap.h b/include/regmap.h
index 9ada1af..30183c5 100644
--- a/include/regmap.h
+++ b/include/regmap.h
@@ -7,6 +7,8 @@
 #ifndef __REGMAP_H
 #define __REGMAP_H
 
+#include <linux/delay.h>
+
 /**
  * DOC: Overview
  *