RDS: remove unused #include <version.h>

Remove unused #include <version.h> in net/rds/af_rds.c.

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>