b43: N-PHY: initialize last var in calibration function

Reported-by: NLarry Finger <larry.finger@lwfinger.net>
Signed-off-by: NRafał Miłecki <zajec5@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/phy_n.c

@@ -3093,7 +3093,7 @@ static int b43_nphy_cal_tx_iq_lo(struct b43_wldev *dev,
 	int freq;
 	bool avoid = false;
 	u8 length;
-	u16 tmp, core, type, count, max, numb, last, cmd;
+	u16 tmp, core, type, count, max, numb, last = 0, cmd;
 	const u16 *table;
 	bool phy6or5x;