xprtrdma: Remove unused fields from rpcrdma_ia

Clean up. The last use of these fields was in commit 173b8f49


("xprtrdma: Demote "connect" log messages") .

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>