drm/fb_cma_helper: Add support for the fbdev dma-buf API Add support for the new semi-standard fbdev API for dma-buf exports to user space. Change-Id: I8df10b2d214bb75a0c3f42f4c6ce58da9e9573b8 Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Liviu Dudau <liviu.dudau@arm.com> [Ported to gem5's 4.9 kernel. Fix incorrect ref count.] Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>