GCC 11 build fix
During Adafruit Bootloader compilation, I spotted bellow error which do not allow me build project.
``` c
inlined from 'hfclk_running' at lib/tinyusb/src/portable/nordic/nrf5x/dcd_nrf5x.c:785:13:
lib/tinyusb/src/portable/nordic/nrf5x/dcd_nrf5x.c:792:31: error: 'is_running' may be used uninitialized [-Werror=maybe-uninitialized]
792 |     return (is_running ? true : false);
|            ~~~~~~~~~~~~~~~~~~~^~~~~~~~
```
@@ -787,7 +787,7 @@ static bool hfclk_running(void)
#ifdef SOFTDEVICE_PRESENT
if ( is_sd_enabled() )
{
- uint32_t is_running;
+ uint32_t is_running = 0;
(void) sd_clock_hfclk_is_running(&is_running);
return (is_running ? true : false);
}
