Use defvar-keymap in play/*.el

Use defvar-keymap in play/*.el

* lisp/play/5x5.el (5x5-mode-map):
* lisp/play/blackbox.el (blackbox-mode-map):
* lisp/play/bubbles.el (bubbles-mode-map):
* lisp/play/decipher.el (decipher-mode-map):
* lisp/play/doctor.el (doctor-mode-map):
* lisp/play/gametree.el (gametree-mode-map):
* lisp/play/gomoku.el (gomoku-mode-map):
* lisp/play/mpuz.el (mpuz-mode-map):
* lisp/play/pong.el (pong-mode-map):
* lisp/play/solitaire.el (solitaire-mode-map): Use defvar-keymap.