staging: lustre: statahead: remove incorrect test on agl_list_empty()

Including agl_list_empty() in the wait_event_idle() condition
is pointless as the body of the loop doesn't do anything
about the agl list.
So if the list wasn't empty, the while loop would spin
indefinitely.

The test was removed in the lustre-release commit
672ab0e00d61 ("LU-3270 statahead: small fixes and cleanup"),
but not in the Linux commit 5231f765 ("staging: lustre:
statahead: small fixes and cleanup").

Fixes: 5231f765 ("staging: lustre: statahead: small fixes and cleanup")
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/statahead.c

@@ -1124,7 +1124,6 @@ static int ll_statahead_thread(void *arg)
 	while (thread_is_running(sa_thread)) {
 		wait_event_idle(sa_thread->t_ctl_waitq,
 				sa_has_callback(sai) ||
-				!agl_list_empty(sai) ||
 				!thread_is_running(sa_thread));
 
 		sa_handle_callback(sai);