ieee802154: cc2520: check for return values in cc2520_filter()

neither ram nor register write return values have been checked here.
Checking both now. Assign ret with 0 as all other assignments are inside
if blocks and might not happen before we return ret.

CID: 1230469
Signed-off-by: Stefan Schmidt <stefan@osg.samsung.com>
Acked-by: Varka Bhadram <varkabhadram@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/net/ieee802154/cc2520.c

@@ -590,20 +590,21 @@ cc2520_filter(struct ieee802154_hw *hw,
 	      struct ieee802154_hw_addr_filt *filt, unsigned long changed)
 {
 	struct cc2520_private *priv = hw->priv;
+	int ret = 0;
 
 	if (changed & IEEE802154_AFILT_PANID_CHANGED) {
 		u16 panid = le16_to_cpu(filt->pan_id);
 
 		dev_vdbg(&priv->spi->dev,
 			 "cc2520_filter called for pan id\n");
-		cc2520_write_ram(priv, CC2520RAM_PANID,
+		ret = cc2520_write_ram(priv, CC2520RAM_PANID,
 				       sizeof(panid), (u8 *)&panid);
 	}
 
 	if (changed & IEEE802154_AFILT_IEEEADDR_CHANGED) {
 		dev_vdbg(&priv->spi->dev,
 			 "cc2520_filter called for IEEE addr\n");
-		cc2520_write_ram(priv, CC2520RAM_IEEEADDR,
+		ret = cc2520_write_ram(priv, CC2520RAM_IEEEADDR,
 				       sizeof(filt->ieee_addr),
 				       (u8 *)&filt->ieee_addr);
 	}
@@ -613,7 +614,7 @@ cc2520_filter(struct ieee802154_hw *hw,
 
 		dev_vdbg(&priv->spi->dev,
 			 "cc2520_filter called for saddr\n");
-		cc2520_write_ram(priv, CC2520RAM_SHORTADDR,
+		ret = cc2520_write_ram(priv, CC2520RAM_SHORTADDR,
 				       sizeof(addr), (u8 *)&addr);
 	}
 
@@ -621,12 +622,14 @@ cc2520_filter(struct ieee802154_hw *hw,
 		dev_vdbg(&priv->spi->dev,
 			 "cc2520_filter called for panc change\n");
 		if (filt->pan_coord)
-			cc2520_write_register(priv, CC2520_FRMFILT0, 0x02);
+			ret = cc2520_write_register(priv, CC2520_FRMFILT0,
+						    0x02);
 		else
-			cc2520_write_register(priv, CC2520_FRMFILT0, 0x00);
+			ret = cc2520_write_register(priv, CC2520_FRMFILT0,
+						    0x00);
 	}
 
-	return 0;
+	return ret;
 }
 
 static inline int cc2520_set_tx_power(struct cc2520_private *priv, s32 mbm)