When multiple async FDs were allowed to exist the idea was for all
broadcast events to be delivered to all async FDs, however
IB_EVENT_DEVICE_FATAL was missed.

Instead of having ib_uverbs_free_hw_resources() special case the global
async_fd, have it cause the event during the uobject destruction. Every
async fd is now a uobject so simply generate the IB_EVENT_DEVICE_FATAL
while destroying the async fd uobject. This ensures every async FD gets a
copy of the event.

Fixes: d680e88e ("RDMA/core: Add UVERBS_METHOD_ASYNC_EVENT_ALLOC")
Link: https://lore.kernel.org/r/20200507063348.98713-3-leon@kernel.orgSigned-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>