Rollback bgt to bgtu; wakeup hart1 after initialization on K210

platform/k210/src/main.rs

@@ -211,6 +211,10 @@ fn main() -> ! {
             pac::PLIC::unmask(mhartid::read(), Interrupt::GPIOHS0);
         }
         boot.clear_interrupt_pending_bits();
+
+        // wake other harts, especially hart1 on k210
+        k210_hal::clint::msip::set_ipi(1);
+        k210_hal::clint::msip::clear_ipi(1);
     }
     
     unsafe {