env: Move env_get_f() to env.h

Move this function over to the new header file.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/board/micronas/vct/vct.c b/board/micronas/vct/vct.c
index af3f11e..e73d16d 100644
--- a/board/micronas/vct/vct.c
+++ b/board/micronas/vct/vct.c
@@ -7,6 +7,7 @@
 
 #include <common.h>
 #include <command.h>
+#include <env.h>
 #include <netdev.h>
 #include <asm/mipsregs.h>
 #include "vct.h"