video: mmpdisp: add spi port in display controller

Add spi port support in mmp display controller.  This port is from display
controller and for panel usage.  This driver implemented and registered as
a spi master.

Signed-off-by: Zhou Zhu <zzhu3@marvell.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Lisa Du <cldu@marvell.com>
Cc: Guoqing Li <ligq@marvell.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>