drm/exynos: Set fbdev FBINFO_VIRTFB flag

Mark the framebuffer with FBINFO_VIRTFB. The framebuffer range is
in DMA-able memory and should be accessed with the CPU's regular
memory ops.

v2:
* drop FBINFO_FLAG_DEFAULT

Signed-off-by: Thomas Zimmermann <[e-mail]>
Reviewed-by: Javier Martinez Canillas <[e-mail]>
Acked-by : Inki Dae <[e-mail]>
Acked-by: Maxime Ripard <[e-mail]>
Cc: Inki Dae <[e-mail]>
Cc: Seung-Woo Kim <[e-mail]>
Cc: Kyungmin Park <[e-mail]>
Cc: Krzysztof Kozlowski <[e-mail]>
Cc: Alim Akhtar <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/exynos/exynos_drm_fbdev.c

···
 	offset = fbi->var.xoffset * fb->format->cpp[0];
 	offset += fbi->var.yoffset * fb->pitches[0];
 
+	fbi->flags |= FBINFO_VIRTFB;
 	fbi->screen_buffer = exynos_gem->kvaddr + offset;
 	fbi->screen_size = size;
 	fbi->fix.smem_len = size;