common: Move ARM cache operations out of common.h

These functions are CPU-related and do not use driver model. Move them to
cpu_func.h

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/net/ag7xxx.c b/drivers/net/ag7xxx.c
index 7f1dee4..804d5c2 100644
--- a/drivers/net/ag7xxx.c
+++ b/drivers/net/ag7xxx.c
@@ -7,6 +7,7 @@
  */
 
 #include <common.h>
+#include <cpu_func.h>
 #include <dm.h>
 #include <errno.h>
 #include <miiphy.h>