ERR_PTR() dereference in net/rds/ib.c

rdma_create_id() doesn't return NULL, only ERR_PTR().

Found by smatch (http://repo.or.cz/w/smatch.git).  Compile tested.

regards,
dan carpenter

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>