Fix for #3266: ensure SPI lock is free after a soft reboot

shared-module/board/__init__.c

@@ -166,6 +166,8 @@ void reset_board_busses(void) {
         #endif
     }
     #endif
+    // make sure SPI lock is not held over a soft reset
+    common_hal_busio_spi_unlock(&spi_obj);
     if (!display_using_spi) {
         spi_singleton = NULL;
     }