RFR : 7178639 : (XXS) Remove incorrect documentation from Deque.push(E e)

[Mike Duigou]

Hello all;

A very small change to review. 

http://cr.openjdk.java.net/~mduigou/JDK-7178639/0/webrev/

The change removes some erroneous documentation from the Deque push() method.

Mike