netfilter: conntrack: remove GC_MAX_EVICTS break

Instead of breaking loop and instant resched, don't bother checking
this in first place (the loop calls cond_resched for every bucket anyway).

Suggested-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>