drm/cirrus: Fix cirrus drm driver for fbdev + qemu

Xorg fbdev driver requires smem_start/smem_len, otherwise
it tries to map 0 bytes as video memory.

Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=856760
Signed-off-by: Martin Koegler <martin.koegler@chello.at>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/cirrus/cirrus_fbdev.c

@@ -233,6 +233,9 @@ static int cirrusfb_create(struct drm_fb_helper *helper,
 	info->apertures->ranges[0].base = cdev->dev->mode_config.fb_base;
 	info->apertures->ranges[0].size = cdev->mc.vram_size;
 
+	info->fix.smem_start = cdev->dev->mode_config.fb_base;
+	info->fix.smem_len = cdev->mc.vram_size;
+
 	info->screen_base = sysram;
 	info->screen_size = size;