octeontx2-af: Set XOFF on other child transmit schedulers during SMQ flush

When multiple transmit scheduler queues feed a TL1 transmit link, the
SMQ flush initiated on a low priority queue might get stuck when a high
priority queue fully subscribes the transmit link. This inturn effects
interface teardown. To avoid this, temporarily XOFF all TL1's other
immediate child transmit scheduler queues and also clear any rate limit
configuration on all the scheduler queues in SMQ(flush) hierarchy.

Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>