wl3501_cs: min_t() cast truncates high bits

wrqu->encoding.length comes from the network administrator.  It's
size u16.  We want to limit "tocopy" to the smallest value of either
"len_keys", "wrqu->encoding.length" or 100.  But because .length
gets cast from u16 to u8 we might use a random, smaller value than
the was desired.  It's probably not very serious, but we may as well
fix it.

Btw, this is from code auditing and not from testing.  I don't know
if this affects anyone in real life.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/wl3501_cs.c

@@ -1781,7 +1781,7 @@ static int wl3501_get_encode(struct net_device *dev,
 				  keys, len_keys);
 	if (rc)
 		goto out;
-	tocopy = min_t(u8, len_keys, wrqu->encoding.length);
+	tocopy = min_t(u16, len_keys, wrqu->encoding.length);
 	tocopy = min_t(u8, tocopy, 100);
 	wrqu->encoding.length = tocopy;
 	memcpy(extra, keys, tocopy);