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/drivers/spi/zynq_spi.c b/drivers/spi/zynq_spi.c
index b59b876..e3bad55 100644
--- a/drivers/spi/zynq_spi.c
+++ b/drivers/spi/zynq_spi.c
@@ -13,6 +13,7 @@
 #include <spi.h>
 #include <time.h>
 #include <asm/io.h>
+#include <linux/delay.h>
 
 DECLARE_GLOBAL_DATA_PTR;