adbd: rename daemon/usb.cpp to daemon/usb_legacy.cpp.

Change-Id: I0b369d1653220f7d9b542ad06998c5c2c3e129a2
Test: mma
diff --git a/adb/Android.bp b/adb/Android.bp
index 7cfa371..d7eb870 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -313,8 +313,8 @@
     srcs: libadb_srcs + libadb_posix_srcs + [
         "daemon/auth.cpp",
         "daemon/jdwp_service.cpp",
-        "daemon/usb.cpp",
         "daemon/usb_ffs.cpp",
+        "daemon/usb_legacy.cpp",
     ],
 
     local_include_dirs: [