virtio-blk: don't lock AioContext in the submission code path

virtio-blk: don't lock AioContext in the submission code path

There is no need to acquire the AioContext lock around blk_aio_*() or
blk_get_geometry() anymore. I/O plugging (defer_call()) also does not
require the AioContext lock anymore.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230914140101.1065008-5-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>