drivers/video/fbdev/fb-puv3.c: Add header files for function unifb_mmap

Function unifb_mmap calls functions which are defined in linux/mm.h
and asm/pgtable.h

The related error (for unicore32 with unicore32_defconfig):
	CC      drivers/video/fbdev/fb-puv3.o
	drivers/video/fbdev/fb-puv3.c: In function 'unifb_mmap':
	drivers/video/fbdev/fb-puv3.c:646: error: implicit declaration of
				      function 'vm_iomap_memory'
	drivers/video/fbdev/fb-puv3.c:646: error: implicit declaration of
				      function 'pgprot_noncached'

Signed-off-by: Zhichuang Sun <sunzc522@gmail.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Joe Perches <joe@perches.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: linux-fbdev@vger.kernel.org
Acked-by: Xuetao Guan <gxt@mprc.pku.edu.cn>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>