net: amd-xgbe: add missed tasklet_kill

The driver does not call tasklet_kill in several places.
Add the calls to fix it.

Fixes: 85b85c85

 ("amd-xgbe: Re-issue interrupt if interrupt status not cleared")
Signed-off-by: Jiguang Xiao <jiguang.xiao@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>