net: thunderx: Fix memory leak while tearing down interface

Fixed 'tso_hdrs' memory not being freed properly.
Also fixed SQ skbuff maintenance issues.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@caviumnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>