Replace -[IOBluetoothL2CAPChannel getDevice] with -[IOBluetoothL2CAPChannel device].

The former method is deprecated, the latter is not. They have the same
functionality.
https://developer.apple.com/library/mac/releasenotes/General/MacOSXLionAPIDiffs/IOBluetooth.html

BUG=592663

Review URL: https://codereview.chromium.org/1813533002

Cr-Commit-Position: refs/heads/master@{#381618}

device/bluetooth/bluetooth_l2cap_channel_mac.mm

@@ -116,7 +116,7 @@ void BluetoothL2capChannelMac::SetSocket(BluetoothSocketMac* socket) {
 }
 
 IOBluetoothDevice* BluetoothL2capChannelMac::GetDevice() {
-  return [channel_ getDevice];
+  return [channel_ device];
 }
 
 uint16_t BluetoothL2capChannelMac::GetOutgoingMTU() {
@@ -142,7 +142,7 @@ void BluetoothL2capChannelMac::OnChannelOpenComplete(
   }
 
   socket()->OnChannelOpenComplete(
-      BluetoothClassicDeviceMac::GetDeviceAddress([channel getDevice]), status);
+      BluetoothClassicDeviceMac::GetDeviceAddress([channel device]), status);
 }
 
 void BluetoothL2capChannelMac::OnChannelClosed(