Staging: sm7xx: add a new framebuffer driver

Staging: sm7xx: add a new framebuffer driver

Yeeloong netbook has a sm712 video card, need this driver, but it is not
ready to upstream yet, so, go to drivers/staing at first.

This source code is originally from Silicon Motion Technology Corp, and
maintained at http://dev.lemote.com/code/linux_loongson for YeeLoong
netbook. I have done a lot of cleanups for it and merged it into my git
repository at http://dev.lemote.com/code/rt4ls.

Thanks to Simon for testing it on a little-endian x86 platform.

Thanks to Olivier Croset <olivier.croset@actis-computer.com> for
reporting the problem about __BIG_ENDIAN compiling problem and send a
relative patch.

The suspend/resume and blank support are contributed by Jason from
Silicon Motion Technology.

Tested-by: Simon Braunschmidt <sbraun@emlix.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>