env: Move env_init() to env.h

Move env_init() over to the new header file.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

common/board_f.c

@@ -14,6 +14,7 @@
 #include <console.h>
 #include <cpu.h>
 #include <dm.h>
+#include <env.h>
 #include <environment.h>
 #include <fdtdec.h>
 #include <fs.h>