userns: Remove unnecessary cast to struct user_struct when copying cred->user.

In struct cred the user member is and has always been declared struct user_struct *user.
At most a constant struct cred will have a constant pointer to non-constant user_struct
so remove this unnecessary cast.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/kernel/sys.c b/kernel/sys.c
index e7006eb..f7a4351 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -209,7 +209,7 @@
 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
 			break;
 		case PRIO_USER:
-			user = (struct user_struct *) cred->user;
+			user = cred->user;
 			if (!who)
 				who = cred->uid;
 			else if ((who != cred->uid) &&
@@ -274,7 +274,7 @@
 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
 			break;
 		case PRIO_USER:
-			user = (struct user_struct *) cred->user;
+			user = cred->user;
 			if (!who)
 				who = cred->uid;
 			else if ((who != cred->uid) &&