sch_hfsc: fix null pointer deref and double free on init failure

sch_hfsc: fix null pointer deref and double free on init failure

commit 3bdac362a2f89ed3e148fa6f38c5f5d858f50b1a upstream.

Depending on where ->init fails we can get a null pointer deref due to
uninitialized hires timer (watchdog) or a double free of the qdisc hash
because it is already freed by ->destroy().

Fixes: 8d5537387505 ("net/sched/hfsc: allocate tcf block for hfsc root class")
Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: sch_hfsc doesn't use a tcf block]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>