octeontx2-pf: Free pending and dropped SQEs

On interface down, the pending SQEs in the NIX get dropped
or drained out during SMQ flush. But skb's pointed by these
SQEs never get free or updated to the stack as respective CQE
never get added.
This patch fixes the issue by freeing all valid skb's in SQ SG list.

Fixes: b1bc8457 ("octeontx2-pf: Cleanup all receive buffers in SG descriptor")
Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>