RDS/IB: 4KB receive buffers get posted by mistake on 16KB frag connections.

RDS/IB: 4KB receive buffers get posted by mistake on 16KB frag connections.

When connections are at 4KB fragments and then it moves to 16KB frags
(for example during uek2 to uek4 upgrade) we see 4KB buffers getting
posted on 16KB connections. This is happening because the 4KB buffers
(buffers from previous connection before the move to 16KB) are getting
added back to the current connection's (16KB) cache.

We will fix this by doing the following.

1) When the recv buffers get freed/released after either the application
   is done reading it or the socket gets closed (process dies, etc.)
   and RDS/IB decides to add that buffer back into the current cache,
   make sure the frag size matches with that of the current connection.

2) When recv completion reports IB_WC_LOC_LEN_ERR, mark the connection state
   as "buffers need to be rebuilt during reconnection". And at the time of
   reconnect rebuild the cache even though the "frag size of the connection"
   has not changed.

Orabug: 25920916

Reviewed-by: Rama Nichanamatlu <rama.nichanamatlu@oracle.com>
Reviewed-by: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>
Signed-off-by: Venkat Venkatsubra <venkat.x.venkatsubra@oracle.com>