HID class: handle host restart gracefully

Upstream/Middlewares/ST/STM32_USB_Device_Library/Class/HID/Src/usbd_hid.c

@@ -298,7 +298,6 @@ static uint8_t  USBD_HID_Init (USBD_HandleTypeDef *pdev,
 static uint8_t  USBD_HID_DeInit (USBD_HandleTypeDef *pdev, 
                                  uint8_t cfgidx)
 {
-  ActiveReportDescriptor = NULL;
   Upstream_HID_DeInit();
 
   /* Close HID EPs */

Upstream/Src/upstream_hid.c

@@ -55,6 +55,13 @@ HAL_StatusTypeDef Upstream_HID_GetNextReport(UpstreamHidSendReportCallback callb
         return HAL_ERROR;
     }
 
+    //Just return if we already have an outstanding request
+    if (ReportCallback != NULL)
+    {
+        return HAL_OK;
+    }
+    ReportCallback = callback;
+
     //Release packet used for last transaction (if any)
     if (UpstreamHidPacket != NULL)
     {
@@ -62,8 +69,6 @@ HAL_StatusTypeDef Upstream_HID_GetNextReport(UpstreamHidSendReportCallback callb
         UpstreamHidPacket = NULL;
     }
 
-    ReportCallback = callback;
-
     freePacket = Upstream_GetFreePacketImmediately();
     if (freePacket == NULL)
     {