cifs: remove unused function cifs_oplock_break_wait

Commit 74316201 ("sched: Remove proliferation of wait_on_bit() action
functions") has removed the call to cifs_oplock_break_wait, making this
function unused; remove it.

This fixes the following compilation warning:

  fs/cifs/misc.c:578:1: warning: ‘cifs_oplock_break_wait’ defined but not used [-Wunused-function]
Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net>
Cc: Steve French <sfrench@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/misc.c

@@ -574,13 +574,6 @@ void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 		cinode->oplock = 0;
 }
 
-static int
-cifs_oplock_break_wait(void *unused)
-{
-	schedule();
-	return signal_pending(current) ? -ERESTARTSYS : 0;
-}
-
 /*
  * We wait for oplock breaks to be processed before we attempt to perform
  * writes.