RDMA/core: Remove ucontext->closing

Nothing reads this any more, and the reason for its existence has passed
due to the deferred fput() scheme.

Fixes: 8ea1f989aa07 ("drivers/IB,usnic: reduce scope of mmap_sem")
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Leon Romanovsky <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/core/rdma_core.c

···
 	if (!ufile->ucontext)
 		goto done;
 
-	ufile->ucontext->closing = true;
 	ufile->ucontext->cleanup_retryable = true;
 	while (!list_empty(&ufile->uobjects))
 		if (__uverbs_cleanup_ufile(ufile, reason)) {

include/rdma/ib_verbs.h

···
 struct ib_ucontext {
 	struct ib_device       *device;
 	struct ib_uverbs_file  *ufile;
-	/*
-	 * 'closing' can be read by the driver only during a destroy callback,
-	 * it is set when we are closing the file descriptor and indicates
-	 * that mm_sem may be locked.
-	 */
-	bool closing;
 
 	bool cleanup_retryable;