MIPS: Yeeloong 2F: Add board specific suspend support

MIPS: Yeeloong 2F: Add board specific suspend support

Lemote Loongson 2F family machines need an external interrupt to wake the
system from the suspend mode.

For YeeLoong 2F and Mengloong 2F setup the keyboard interrupt as the wakeup
interrupt.

The new Fuloong 2F and LingLoong 2F have a button to directly send an
interrupt to the CPU so there is no need to setup an interrupt.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: yanh@lemote.com
Cc: huhb@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: linux-pm@lists.linux-foundation.org
Patchwork: http://patchwork.linux-mips.org/patch/630/
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>