rdma/cxgb4: Add support for 64Byte cqes

This patch adds support for iw_cxb4 to extend cqes from existing 32Byte
size to 64Byte.

Also includes adds backward compatibility support (for 32Byte) to work
with older libraries.

Signed-off-by: Raju Rangoju <rajur@chelsio.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>