If SMI AH is not destroyed before de-allocating the PD, it would result in
non-zero PD use count when de-allocating the PD, triggering a WARN_ON() at
drivers/infiniband/core/verbs.c:284 ib_dealloc_pd+0x69/0xb0 [ib_core]()
when unloading the qib driver on systems with dual-port card.

This problem has always been there in qib and was detected only after the
commit 7dd78647 ("IB/core: Make ib_dealloc_pd return void") introduced
a WARN_ON in ib_dealloc_pd() that triggers if a PD's use count is non-zero
before de-allocating the PD.

Below is the call trace from the dmesg log.

[ 7264.966129] Call Trace:
[ 7264.969652]  [<ffffffff81338470>] dump_stack+0x44/0x64
[ 7264.976181]  [<ffffffff81086bb6>] warn_slowpath_common+0x86/0xc0
[ 7264.983656]  [<ffffffff81086cfa>] warn_slowpath_null+0x1a/0x20
[ 7264.990961]  [<ffffffffa025c2d9>] ib_dealloc_pd+0x69/0xb0 [ib_core]
[ 7264.998717]  [<ffffffffa0044de8>] ib_mad_port_close+0xb8/0x120 [ib_mad]
[ 7265.006866]  [<ffffffffa0044ebf>] ib_mad_remove_device+0x6f/0xc0 [ib_mad]
[ 7265.015224]  [<ffffffffa025fc87>] ib_unregister_device+0xa7/0x140 [ib_core]
[ 7265.023738]  [<ffffffffa04b5b79>] rvt_unregister_device+0x29/0x80 [rdmavt]
[ 7265.032181]  [<ffffffffa088d2a2>] qib_unregister_ib_device+0x22/0x210 [ib_qib]
[ 7265.040993]  [<ffffffffa085f73f>] qib_remove_one+0x1f/0x250 [ib_qib]
[ 7265.048823]  [<ffffffff8137a319>] pci_device_remove+0x39/0xc0
[ 7265.055984]  [<ffffffff81466a1a>] __device_release_driver+0x9a/0x140
[ 7265.063821]  [<ffffffff81466bc8>] driver_detach+0xb8/0xc0
[ 7265.070579]  [<ffffffff81465a15>] bus_remove_driver+0x55/0xd0
[ 7265.077717]  [<ffffffff8146732c>] driver_unregister+0x2c/0x50
[ 7265.084849]  [<ffffffff813789ba>] pci_unregister_driver+0x2a/0x80
[ 7265.092366]  [<ffffffffa08921bd>] qib_ib_cleanup+0x37/0x65 [ib_qib]
[ 7265.100068]  [<ffffffff811096d0>] SyS_delete_module+0x190/0x220
[ 7265.107379]  [<ffffffff816a7bae>] entry_SYSCALL_64_fastpath+0x12/0x71
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>