Spinlock bug in poll.rs

[yexuanyang]

RROS/kernel/rros/poll.rs

Lines 379 to 382 in 8368c16

 flags = head.watchpoints.irq_lock_noguard(); 
 list_for_each_entry!( 
     poco, 
     head.watchpoints.lock().deref(), 

Try to acquire spinlock when spinlock is already locked.

[Hu Jiangtao]

Fixed.