IB/mlx4: Fix potential deadlock when sending mad to wire

IB/mlx4: Fix potential deadlock when sending mad to wire

commit 90c1d8b6350cca9d8a234f03c77a317a7613bcee upstream.

send_mad_to_wire takes the same spinlock that is taken in
the interrupt context.  Therefore, it needs irqsave/restore.

Fixes: b9c5d6a64358 ('IB/mlx4: Add multicast group (MCG) paravirtualization for SR-IOV')
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>