IB/mlx4: Fix code indentation in QP1 MAD flow

The indentation in the QP1 GRH flow in procedure build_mlx_header is
really confusing. Fix it, in preparation for a commit which touches
this code.

Fixes: 1ffeb2eb

 ("IB/mlx4: SR-IOV IB context objects and proxy/tunnel SQP support")
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>