userns: Replace user_ns_map_uid and user_ns_map_gid with from_kuid and from_kgid

These function are no longer needed replace them with their more useful equivalents.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/kernel/signal.c b/kernel/signal.c
index 2734dc9..d630327 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1026,7 +1026,7 @@
 static inline uid_t map_cred_ns(const struct cred *cred,
 				struct user_namespace *ns)
 {
-	return user_ns_map_uid(ns, cred, cred->uid);
+	return from_kuid_munged(ns, cred->uid);
 }
 
 #ifdef CONFIG_USER_NS