MIPS: Yeeloong 2F: Add basic EC operations

YeeLoong2F has a KB3310b embedded controller. Add basic operations for
future related drivers and board support.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/684/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>