nl80211: Eliminate reference to BUS_ID_SIZE.

It's going away.  Just leave the constant "20" here so that
behavior doesn't change.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/wireless/nl80211.c

@@ -57,7 +57,7 @@ static int get_drv_dev_by_info_ifindex(struct nlattr **attrs,
 static struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] __read_mostly = {
 	[NL80211_ATTR_WIPHY] = { .type = NLA_U32 },
 	[NL80211_ATTR_WIPHY_NAME] = { .type = NLA_NUL_STRING,
-				      .len = BUS_ID_SIZE-1 },
+				      .len = 20-1 },
 	[NL80211_ATTR_WIPHY_TXQ_PARAMS] = { .type = NLA_NESTED },
 	[NL80211_ATTR_WIPHY_FREQ] = { .type = NLA_U32 },
 	[NL80211_ATTR_WIPHY_CHANNEL_TYPE] = { .type = NLA_U32 },