net: bridge: Allow base 16 inputs in sysfs

Cited commit converted simple_strtoul() to kstrtoul() as suggested by
the former's documentation. However, it also forced all the inputs to be
decimal resulting in user space breakage.

Fix by setting the base to '0' so that the base is automatically
detected.

Before:

 # ip link add name br0 type bridge vlan_filtering 1
 # echo "0x88a8" > /sys/class/net/br0/bridge/vlan_protocol
 bash: echo: write error: Invalid argument

After:

 # ip link add name br0 type bridge vlan_filtering 1
 # echo "0x88a8" > /sys/class/net/br0/bridge/vlan_protocol
 # echo $?
 0

Fixes: 520fbdf7fb ("net/bridge: replace simple_strtoul to kstrtol")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Link: https://lore.kernel.org/r/20211124101122.3321496-1-idosch@idosch.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/bridge/br_sysfs_br.c

@@ -41,7 +41,7 @@ static ssize_t store_bridge_parm(struct device *d,
 	if (!ns_capable(dev_net(br->dev)->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
-	err = kstrtoul(buf, 10, &val);
+	err = kstrtoul(buf, 0, &val);
 	if (err != 0)
 		return err;