IB/mad: Fix indentation

Make indentation consistent. Detected by smatch.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Hal Rosenstock <hal@mellanox.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Reviewed-By: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Hal Rosenstock <hal@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Doug Ledford <dledford@redhat.com>