adb: remove support for legacy f_adb interface.

Everything should be using the functionfs interface instead by now.

Bug: http://b/34228376
Test: grepping for f_adb, android_adb in source tree
Test: m
Change-Id: I6bc41049c49a867499832588dac8ed108c636c11
diff --git a/adb/daemon/main.cpp b/adb/daemon/main.cpp
index 78434a0..1a39f6a 100644
--- a/adb/daemon/main.cpp
+++ b/adb/daemon/main.cpp
@@ -170,7 +170,7 @@
     drop_privileges(server_port);
 
     bool is_usb = false;
-    if (access(USB_ADB_PATH, F_OK) == 0 || access(USB_FFS_ADB_EP0, F_OK) == 0) {
+    if (access(USB_FFS_ADB_EP0, F_OK) == 0) {
         // Listen on USB.
         usb_init();
         is_usb = true;