cfg80211: fix wext-compat for setting rate to 'auto'

Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/wext-compat.c b/net/wireless/wext-compat.c
index 966d2f0..b17eeae 100644
--- a/net/wireless/wext-compat.c
+++ b/net/wireless/wext-compat.c
@@ -1214,7 +1214,7 @@
 
 	memset(&mask, 0, sizeof(mask));
 	fixed = 0;
-	maxrate = 0;
+	maxrate = (u32)-1;
 
 	if (rate->value < 0) {
 		/* nothing */