fix I2C slave addressing

With the recent device handling changes the I2C slave addressing code
was broken. With current code, if a slave with the correct address is

not found on the bus the last scanned slave on the bus will be
addressed. This is wrong. Please find attached a patch to fix it.
Signed-off-by: NJuha Riihimäki <juha.riihimaki@nokia.com>
Acked-by: NRiku Voipio <riku.voipio@iki.fi>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

hw/i2c.c

@@ -85,10 +85,12 @@ int i2c_start_transfer(i2c_bus *bus, uint8_t address, int recv)
     i2c_slave *slave = NULL;
 
     QLIST_FOREACH(qdev, &bus->qbus.children, sibling) {
-        slave = I2C_SLAVE_FROM_QDEV(qdev);
-        if (slave->address == address)
+        i2c_slave *candidate = I2C_SLAVE_FROM_QDEV(qdev);
+        if (candidate->address == address) {
+            slave = candidate;
             break;
         }
+    }
 
     if (!slave)
         return 1;