Revert "adb: close ep0 on disconnection."

This reverts commit 69e97e4b.

Bug: 28932120
Change-Id: I5e2569abed316c089886556c432bfe59bca08549
(cherry picked from commit 57de0514)

adb/usb_linux_client.cpp

@@ -400,6 +400,7 @@ static bool init_functionfs(struct usb_handle *h)
     v2_descriptor.os_header = os_desc_header;
     v2_descriptor.os_desc = os_desc_compat;
 
+    if (h->control < 0) { // might have already done this before
         D("OPENING %s", USB_FFS_ADB_EP0);
         h->control = adb_open(USB_FFS_ADB_EP0, O_RDWR);
         if (h->control < 0) {
@@ -428,6 +429,7 @@ static bool init_functionfs(struct usb_handle *h)
             D("[ %s: writing strings failed: errno=%d]", USB_FFS_ADB_EP0, errno);
             goto err;
         }
+    }
 
     h->bulk_out = adb_open(USB_FFS_ADB_OUT, O_RDWR);
     if (h->bulk_out < 0) {
@@ -554,7 +556,6 @@ static void usb_ffs_close(usb_handle *h) {
     h->kicked = false;
     adb_close(h->bulk_out);
     adb_close(h->bulk_in);
-    adb_close(h->control);
     // Notify usb_adb_open_thread to open a new connection.
     adb_mutex_lock(&h->lock);
     h->open_new_connection = true;