RDMA/ipoib: Return void from ipoib_ib_dev_stop()

[ Upstream commit 95a5631f6c9f3045f26245e6045244652204dfdb ]

The return value from ipoib_ib_dev_stop() is always 0 - change it to be
void.

Link: https://lore.kernel.org/r/20200623105236.18683-1-kamalheib1@gmail.com


Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>