env: Move env_set() to env.h

Move env_set() over to the new header file.

Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/exports.h b/include/exports.h
index bf8d53c..147a00f 100644
--- a/include/exports.h
+++ b/include/exports.h
@@ -3,6 +3,7 @@
 
 #ifndef __ASSEMBLY__
 #ifdef CONFIG_PHY_AQUANTIA
+#include <env.h>
 #include <phy_interface.h>
 #endif