route: release dst_entry.hh_cache when handling redirects

route: release dst_entry.hh_cache when handling redirects

Stable-3.0 commit 42ab5316 (ipv4: fix redirect handling) was
backport of mainline commit 9cc20b26 from 3.2-rc3 where hh
member of struct dst_entry was already gone.

However, in 3.0 we still have it and we have to clean it as
well, otherwise it keeps pointing to the cleaned up (and
unusable) hh_cache entry and packets cannot be sent out.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>