Allow USB endpoint_add to accept mbed::Callback

In this way we can use the USBDevice infrastructure without deriving directly from USBDevice.

Author: facchinm

drivers/internal/USBDevice.h

@@ -22,6 +22,7 @@
 #include "USBDevice_Types.h"
 #include "USBPhy.h"
 #include "mbed_critical.h"
+#include "Callback.h"
 
 /**
  * \defgroup drivers_USBDevice USBDevice class
@@ -139,7 +140,7 @@ class USBDevice: public  USBPhyEvents {
     * @param callback Method pointer to be called when a packet is transferred
     * @returns true if successful, false otherwise
     */
-    bool endpoint_add(usb_ep_t endpoint, uint32_t max_packet, usb_ep_type_t type, ep_cb_t callback = NULL);
+    bool endpoint_add(usb_ep_t endpoint, uint32_t max_packet, usb_ep_type_t type, mbed::Callback<void()> callback = NULL);
 
     /**
     * Add an endpoint
@@ -153,7 +154,7 @@ class USBDevice: public  USBPhyEvents {
     template<typename T>
     bool endpoint_add(usb_ep_t endpoint, uint32_t max_packet, usb_ep_type_t type, void (T::*callback)())
     {
-        return endpoint_add(endpoint, max_packet, type, static_cast<ep_cb_t>(callback));
+        return endpoint_add(endpoint, max_packet, type, mbed::callback(this, static_cast<ep_cb_t>(callback)));
     }
 
     /**
@@ -540,7 +541,7 @@ class USBDevice: public  USBPhyEvents {
     void _complete_set_interface();
 
     struct endpoint_info_t {
-        ep_cb_t callback;
+        mbed::Callback<void()> callback;
         uint16_t max_packet_size;
         uint16_t transfer_size;
         uint8_t flags;

drivers/source/usb/USBDevice.cpp

@@ -937,7 +937,7 @@ void USBDevice::out(usb_ep_t endpoint)
     MBED_ASSERT(info->pending >= 1);
     info->pending -= 1;
     if (info->callback) {
-        (this->*(info->callback))();
+        info->callback();
     }
 }
 
@@ -955,7 +955,7 @@ void USBDevice::in(usb_ep_t endpoint)
     MBED_ASSERT(info->pending >= 1);
     info->pending -= 1;
     if (info->callback) {
-        (this->*(info->callback))();
+        info->callback();
     }
 }
 
@@ -1051,7 +1051,7 @@ void USBDevice::sof_disable()
     unlock();
 }
 
-bool USBDevice::endpoint_add(usb_ep_t endpoint, uint32_t max_packet_size, usb_ep_type_t type, ep_cb_t callback)
+bool USBDevice::endpoint_add(usb_ep_t endpoint, uint32_t max_packet_size, usb_ep_type_t type, mbed::Callback<void()> callback)
 {
     lock();