RDMA/nes: Add missing break to switch.

Static code analyzer cppcheck points out a missing break.

Reported-by: David Binderman <dcb314@hotmail.com>
Addresses: <https://bugzilla.kernel.org/show_bug.cgi?id=47671

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Signed-off-by: Tatyana Nikolova <Tatyana.E.Nikolova@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>