netfilter: flowtable: fix incorrect Kconfig dependencies

Remove default to 'y', this infrastructure is not fundamental for the
flowtable operational.

Add a missing dependency on CONFIG_NF_FLOW_TABLE.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: b0381776 ("netfilter: nf_flow_table: count pending offload workqueue tasks")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/netfilter/Kconfig

@@ -736,9 +736,8 @@ config NF_FLOW_TABLE
 
 config NF_FLOW_TABLE_PROCFS
 	bool "Supply flow table statistics in procfs"
-	default y
+	depends on NF_FLOW_TABLE
 	depends on PROC_FS
-	depends on SYSCTL
 	help
 	  This option enables for the flow table offload statistics
 	  to be shown in procfs under net/netfilter/nf_flowtable.