drm/tegra: Add error check for NVDEC firmware memory allocation

The return value for tegra_drm_alloc was missing an error check.
Add one.
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230413082202.114721-1-cyndis@kapsi.fi

drivers/gpu/drm/tegra/nvdec.c

@@ -274,6 +274,8 @@ static int nvdec_load_falcon_firmware(struct nvdec *nvdec)
 			return err;
 	} else {
 		virt = tegra_drm_alloc(tegra, size, &iova);
+		if (IS_ERR(virt))
+			return PTR_ERR(virt);
 	}
 
 	nvdec->falcon.firmware.virt = virt;