xprtrdma: Throw away reply when version is unrecognized

A reply with an unrecognized value in the version field means the
transport header is potentially garbled and therefore all the fields
are untrustworthy.

Fixes: 59aa1f9a

 ("xprtrdma: Properly handle RDMA_ERROR ... ")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>