selftests: netfilter: nft_flowtable.sh: bump socat timeout to 1m

Now that this test runs in netdev CI it looks like 10s isn't enough
for debug kernels:
selftests: net/netfilter: nft_flowtable.sh
2024/05/10 20:33:08 socat[12204] E write(7, 0x563feb16a000, 8192): Broken pipe
FAIL: file mismatch for ns1 -> ns2
-rw------- 1 root root 37345280 May 10 20:32 /tmp/tmp.Am0yEHhNqI
...

Looks like socat gets zapped too quickly, so increase timeout to 1m.

Could also reduce tx file size for KSFT_MACHINE_SLOW, but its preferrable
to have same test for both debug and nondebug.

Signed-off-by: Florian Westphal <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/netfilter/nft_flowtable.sh

···
 source lib.sh
 
 ret=0
+SOCAT_TIMEOUT=60
 
 nsin=""
 ns1out=""
···
 	local dstport=$4
 	local lret=0
 
-	timeout 10 ip netns exec "$nsb" socat -4 TCP-LISTEN:12345,reuseaddr STDIO < "$nsin" > "$ns2out" &
+	timeout "$SOCAT_TIMEOUT" ip netns exec "$nsb" socat -4 TCP-LISTEN:12345,reuseaddr STDIO < "$nsin" > "$ns2out" &
 	lpid=$!
 
 	busywait 1000 listener_ready
 
-	timeout 10 ip netns exec "$nsa" socat -4 TCP:"$dstip":"$dstport" STDIO < "$nsin" > "$ns1out"
+	timeout "$SOCAT_TIMEOUT" ip netns exec "$nsa" socat -4 TCP:"$dstip":"$dstport" STDIO < "$nsin" > "$ns1out"
 
 	wait $lpid