carl9170: clean up a clamp() call

The parameter order for clamp is supposed to be clamp(value, low, high).
When we write it in this order it's equivalent to
min(head->plcp[3] & 0x7f, 75) which works in this context where the min
is zero.  But it's not a correct use of the API.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/carl9170/rx.c

@@ -427,7 +427,7 @@ static int carl9170_rx_mac_status(struct ar9170 *ar,
 		if (head->plcp[6] & 0x80)
 			status->enc_flags |= RX_ENC_FLAG_SHORT_GI;
 
-		status->rate_idx = clamp(0, 75, head->plcp[3] & 0x7f);
+		status->rate_idx = clamp(head->plcp[3] & 0x7f, 0, 75);
 		status->encoding = RX_ENC_HT;
 		break;