poll: use spinlocks rather than mutexes for use in higher IPLs

kernel-src/include/kernel/poll.h

@@ -3,21 +3,20 @@
 
 #include <kernel/scheduler.h>
 #include <spinlock.h>
-#include <mutex.h>
 
 struct polldata;
 
 typedef struct {
 	thread_t *thread;
 	spinlock_t lock;
-	mutex_t eventlock;
+	spinlock_t eventlock;
 	struct polldata *data;
 	struct polldata *event;
 	size_t size;
 } polldesc_t;
 
 typedef struct {
-	mutex_t lock;
+	spinlock_t lock;
 	struct polldata *data;
 } pollheader_t;
 
@@ -31,7 +30,7 @@ typedef struct polldata {
 } polldata_t;
 
 #define POLL_INITHEADER(x) \
-	MUTEX_INIT(&(x)->lock);
+	SPINLOCK_INIT((x)->lock);
 
 int poll_initdesc(polldesc_t *, size_t size);
 void poll_add(pollheader_t *, polldata_t *, int events);