fix: use log for kernel output

user/src/bin/0sleep.rs

@@ -11,10 +11,11 @@ fn main() -> i32 {
     let current_time = get_time();
     let wait_time = current_time + 3000;
 
+    println!("Sleep~~~~");
     while get_time() < wait_time {
         sys_yield();
     }
 
     println!("Test sleep OK!");
     0
-}
+}

user/src/bin/power_3.rs

@@ -25,4 +25,4 @@ fn main() -> i32 {
     println!("{}^{} = {}(MOD {})", p, iter, s[cur], m);
     println!("Test power_3 OK!");
     0
-}
+}

user/src/bin/power_5.rs

@@ -25,4 +25,4 @@ fn main() -> i32 {
     println!("{}^{} = {}(MOD {})", p, iter, s[cur], m);
     println!("Test power_5 OK!");
     0
-}
+}

user/src/bin/power_7.rs

@@ -25,4 +25,4 @@ fn main() -> i32 {
     println!("{}^{} = {}(MOD {})", p, iter, s[cur], m);
     println!("Test power_7 OK!");
     0
-}
+}