move pine64.py board under pine64 vendor dir

Author: anonymouscowhead

src/adafruit_blinka/board/pine64.py renamed to src/adafruit_blinka/board/pine64/pine64.py

@@ -233,7 +233,7 @@
     from adafruit_blinka.board.hifive_unleashed import *
 
 elif board_id == ap_board.PINE64:
-    from adafruit_blinka.board.pine64 import *
+    from adafruit_blinka.board.pine64.pine64 import *
 
 elif board_id == ap_board.PINEH64:
     from adafruit_blinka.board.pineH64 import *