UPSTREAM: drm/tegra: fb: Add diagnostics for framebuffer modifiers

Add a debug message to let the user know when a framebuffer modifier is
not supported.

Change-Id: Iac3ea90b3c1f2a7674ff7ff0bc7f8af3214bdfed
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvidia/+/2545943
Reviewed-by: svc_kernel_abi <svc_kernel_abi@nvidia.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit

drivers/gpu/drm/tegra/fb.c

@@ -86,6 +86,7 @@ int tegra_fb_get_tiling(struct drm_framebuffer *framebuffer,
 		break;
 
 	default:
+		DRM_DEBUG_KMS("unknown format modifier: %llx\n", modifier);
 		return -EINVAL;
 	}