add new tusb_int_handler(rhport, in_isr) as common irq handler

update tusb_init() to take rhport and role, defined as macro with optional argument for backward compatible

docs/reference/getting_started.rst

@@ -12,22 +12,19 @@ It is relatively simple to incorporate tinyusb to your project
 * Add *your_project/tinyusb/src* to your include path. Also make sure your current include path also contains the configuration file tusb_config.h.
 * Make sure all required macros are all defined properly in tusb_config.h (configure file in demo application is sufficient, but you need to add a few more such as CFG_TUSB_MCU, CFG_TUSB_OS since they are passed by IDE/compiler to maintain a unique configure for all boards).
 * If you use the device stack, make sure you have created/modified usb descriptors for your own need. Ultimately you need to implement all **tud descriptor** callbacks for the stack to work.
-* Add tusb_init() call to your reset initialization code.
-* Call ``tud_int_handler()`` (device) and/or ``tuh_int_handler()`` (host) in your USB IRQ Handler
+* Add tusb_init(rhport, role) call to your reset initialization code.
+* Call ``tusb_int_handler(rhport, in_isr)`` in your USB IRQ Handler
 * Implement all enabled classes's callbacks.
 * If you don't use any RTOSes at all, you need to continuously and/or periodically call tud_task()/tuh_task() function. All of the callbacks and functionality are handled and invoked within the call of that task runner.
 
 .. code-block::
 
-   int main(void)
-   {
+   int main(void) {
      your_init_code();
-     tusb_init(); // initialize tinyusb stack
+     tusb_init(0, TUSB_ROLE_DEVICE); // initialize device stack on roothub port 0
 
-     while(1) // the mainloop
-     {
+     while(1) { // the mainloop
        your_application_code();
-
        tud_task(); // device task
        tuh_task(); // host task
      }