[ewg] [GIT PULL compat-rdma] cxgb4 upstream fix for OFED-4.8

[Steve Wise]

Hey Vlad,

Please pull this commit from my for-vlad branch of 

git://git.openfabrics.org/~swise/compat-rdma

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commit 785e7bf5d83f71fb9e51ca10d7b1a65f901034bf
Author: Potnuri Bharat Teja <bharat at chelsio.com>
Date:   Mon Apr 24 09:51:17 2017 -0700

    iw_cxgb4: Guard against null cm_id in dump_ep/qp
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Thanks,

Steve.