env: Move env_get_ulong() to env.h

Move env_get_ulong() 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/gdsys/p1022/controlcenterd-id.c b/board/gdsys/p1022/controlcenterd-id.c
index 6ac956c..43f5404 100644
--- a/board/gdsys/p1022/controlcenterd-id.c
+++ b/board/gdsys/p1022/controlcenterd-id.c
@@ -12,6 +12,7 @@
 
 #include <common.h>
 #include <dm.h>
+#include <env.h>
 #include <malloc.h>
 #include <fs.h>
 #include <i2c.h>