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/api/api.c b/api/api.c
index 4fc451a..c7f5db7 100644
--- a/api/api.c
+++ b/api/api.c
@@ -11,6 +11,7 @@
 #include <env.h>
 #include <malloc.h>
 #include <env_internal.h>
+#include <linux/delay.h>
 #include <linux/types.h>
 #include <api_public.h>
 #include <u-boot/crc.h>