When synchronous request completion loops are running, the innermost
loop can receive events that can unblock the outer loops, however the
loop clears uloop_cancelled (which is set by the request completion).
This causes the event loop to continue running even while a completion
loop has already been unblocked.
Fix this by not clearing uloop_cancelled for inner loops
Signed-off-by: Felix Fietkau <nbd@openwrt.org>