env: Allow env_attr_walk to pass a priv * to callback

In some cases it can be helpful to have context in the callback about
the calling situation. This is needed for following patches.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/env_flags.c b/common/env_flags.c
index 985f92e..5189f5b 100644
--- a/common/env_flags.c
+++ b/common/env_flags.c
@@ -435,7 +435,7 @@
 /*
  * Call for each element in the list that defines flags for a variable
  */
-static int set_flags(const char *name, const char *value)
+static int set_flags(const char *name, const char *value, void *priv)
 {
 	ENTRY e, *ep;
 
@@ -463,9 +463,9 @@
 	hwalk_r(&env_htab, clear_flags);
 
 	/* configure any static flags */
-	env_attr_walk(ENV_FLAGS_LIST_STATIC, set_flags);
+	env_attr_walk(ENV_FLAGS_LIST_STATIC, set_flags, NULL);
 	/* configure any dynamic flags */
-	env_attr_walk(value, set_flags);
+	env_attr_walk(value, set_flags, NULL);
 
 	return 0;
 }