CRIS: Remove 'TOPDIR' from Makefiles

This patch removes TOPDIR from Cris Makefiles.

Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Andreas Schwab <schwab@suse.de>
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>