cargo clippy & fmt

os/src/syscall/fs.rs

@@ -7,9 +7,9 @@ pub fn sys_write(fd: usize, buf: *const u8, len: usize) -> isize {
             let str = core::str::from_utf8(slice).unwrap();
             print!("{}", str);
             len as isize
-        },
+        }
         _ => {
             panic!("Unsupported fd in sys_write!");
         }
     }
-}
+}