[NET]: Kill stray reference to sock->passcred.

That struct member was deleted, but a comment
was not updated to reflect this.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/net.h b/include/linux/net.h
index 6d997ff..20cb226 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -101,7 +101,6 @@
  *  @sk: internal networking protocol agnostic socket representation
  *  @wait: wait queue for several uses
  *  @type: socket type (%SOCK_STREAM, etc)
- *  @passcred: credentials (used only in Unix Sockets (aka PF_LOCAL))
  */
 struct socket {
 	socket_state		state;