drm: omapdrm: Fix implicit dma_buf fencing

Currently omapdrm driver does not initialize dma_buf_export_info resv
member, which leads to a new dma_resv being allocated and attached to
the exported dma_buf. This leads to the issue that fences created on
dma_buf objects imported by other drivers are ignored by omapdrm, as only
fences in gem object resv are waited on. This leads to various issues like
displaying incomplete frames.

Fix that by initializing dma_buf resv to the resv of the gem object being
exported.

Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Tested-by: Merlijn Wajer <merlijn@wizzup.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1641397018-29872-1-git-send-email-ivo.g.dimitrov.75@gmail.com

drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c

@@ -93,6 +93,7 @@ struct dma_buf *omap_gem_prime_export(struct drm_gem_object *obj, int flags)
 	exp_info.size = omap_gem_mmap_size(obj);
 	exp_info.flags = flags;
 	exp_info.priv = obj;
+	exp_info.resv = obj->resv;
 
 	return drm_gem_dmabuf_export(obj->dev, &exp_info);
 }