IB/core: Expose ib_ucontext from a given ib_uverbs_file

Drivers that use the IOCTL API may have the ib_uverbs_file and need a
way to get the related ib_ucontext from it, this is enabled by this
patch.

Downstream patches from this series will use it.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index dc5d262..995d517 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -4120,4 +4120,6 @@ ib_get_vector_affinity(struct ib_device *device, int comp_vector)
  */
 void rdma_roce_rescan_device(struct ib_device *ibdev);
 
+struct ib_ucontext *ib_uverbs_get_ucontext(struct ib_uverbs_file *ufile);
+
 #endif /* IB_VERBS_H */