drm/nouveau/secboot/acr: fix memory leak

In case memory resources for *bl_desc* were allocated, release
them before return.

Addresses-Coverity-ID: 1472021 ("Resource leak")
Fixes: 0d466901 ("drm/nouveau/secboot/acr: Remove VLA usage")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/secboot/acr_r352.c

@@ -801,6 +801,7 @@ acr_r352_load(struct nvkm_acr *_acr, struct nvkm_falcon *falcon,
 		bl = acr->hsbl_unload_blob;
 	} else {
 		nvkm_error(_acr->subdev, "invalid secure boot blob!\n");
+		kfree(bl_desc);
 		return -EINVAL;
 	}