HID: Renamed fields in HIDDescriptorListNode and HID_Descriptor

In particular HIDDescriptorListNode.cb has been renamed to
HIDDescriptorListNode.descriptor because it contains decriptor data
and not callbacks.

Moreover the HID_Descriptor.descriptor field has been renamed
to HID_Descriptor.data so the structure has now two fields length
and data.

   typedef struct __attribute__((packed)) {
     uint16_t length;
     const void* data;
   } HID_Descriptor;

   class HIDDescriptorListNode {
   public:
     HIDDescriptorListNode *next = NULL;
     const HID_Descriptor *descriptor;
     HIDDescriptorListNode(const HID_Descriptor *d) : descriptor(d) { }
   };

This imply a change in the use of the node from:

  node->cb->lenght
  node->cd->descriptor

to

  node->descriptor->length
  node->descriptor->data

libraries/HID/HID.cpp

@@ -61,7 +61,7 @@ int HID_GetDescriptor(int8_t t)
 		HIDDescriptorListNode* current = rootNode;
 		int total = 0;
 		while(current != NULL) {
-			total += USB_SendControl(TRANSFER_PGM,current->cb->descriptor,current->cb->length);
+			total += USB_SendControl(TRANSFER_PGM,current->descriptor->data,current->descriptor->length);
 			current = current->next;
 		}
 		return total;
@@ -82,7 +82,7 @@ void HID_::AppendDescriptor(HIDDescriptorListNode *node)
 		current->next = node;
 	}
 	modules_count++;
-	sizeof_hidReportDescriptor += (uint16_t)node->cb->length;
+	sizeof_hidReportDescriptor += (uint16_t)node->descriptor->length;
 }
 
 void HID_::SendReport(u8 id, const void* data, int len)

libraries/HID/HID.h

@@ -46,14 +46,14 @@
 
 typedef struct __attribute__((packed)) {
   uint16_t length;
-  const void* descriptor;
+  const void* data;
 } HID_Descriptor;
 
 class HIDDescriptorListNode {
 public:
   HIDDescriptorListNode *next = NULL;
-  const HID_Descriptor * cb;
+  const HID_Descriptor *descriptor;
-  HIDDescriptorListNode(const HID_Descriptor *ncb) {cb = ncb;}
+  HIDDescriptorListNode(const HID_Descriptor *d) : descriptor(d) { }
 };
 
 class HID_