netfilter: x_tables: return -ENOENT for non-existant matches/targets

As Stephen correctly points out, we need to return -ENOENT in
xt_find_match()/xt_find_target() after the patch "netfilter: x_tables:
misuse of try_then_request_module" in order to properly indicate
a non-existant module to the caller.
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/netfilter/x_tables.c

@@ -190,7 +190,7 @@ EXPORT_SYMBOL(xt_unregister_matches);
 struct xt_match *xt_find_match(u8 af, const char *name, u8 revision)
 {
 	struct xt_match *m;
-	int err = 0;
+	int err = -ENOENT;
 
 	if (mutex_lock_interruptible(&xt[af].mutex) != 0)
 		return ERR_PTR(-EINTR);
@@ -235,7 +235,7 @@ EXPORT_SYMBOL_GPL(xt_request_find_match);
 struct xt_target *xt_find_target(u8 af, const char *name, u8 revision)
 {
 	struct xt_target *t;
-	int err = 0;
+	int err = -ENOENT;
 
 	if (mutex_lock_interruptible(&xt[af].mutex) != 0)
 		return ERR_PTR(-EINTR);