adb: libusb: recognize devices with multiple interfaces.

A bug was introduced by commit 8bf37d7a wherein we accidentally only
look at the first interface of a device when checking whether a USB
device was an ADB device or not.

Bug: http://b/38201318
Test: none
Change-Id: I8e8e0963c77cd2cb03538d926ab735f4b57e52b7
diff --git a/adb/client/usb_libusb.cpp b/adb/client/usb_libusb.cpp
index 2508fc1..fc32469 100644
--- a/adb/client/usb_libusb.cpp
+++ b/adb/client/usb_libusb.cpp
@@ -237,7 +237,7 @@
             // TODO: Is this assumption valid?
             LOG(VERBOSE) << "skipping interface with incorrect num_altsetting at " << device_address
                          << " (interface " << interface_num << ")";
-            return;
+            continue;
         }
 
         const libusb_interface_descriptor& interface_desc = interface.altsetting[0];
@@ -245,7 +245,7 @@
                               interface_desc.bInterfaceProtocol)) {
             LOG(VERBOSE) << "skipping non-adb interface at " << device_address << " (interface "
                          << interface_num << ")";
-            return;
+            continue;
         }
 
         LOG(VERBOSE) << "found potential adb interface at " << device_address << " (interface "
@@ -261,7 +261,7 @@
             const uint8_t transfer_type = endpoint_attr & LIBUSB_TRANSFER_TYPE_MASK;
 
             if (transfer_type != LIBUSB_TRANSFER_TYPE_BULK) {
-                return;
+                continue;
             }
 
             if (endpoint_is_output(endpoint_addr) && !found_out) {