nouveau: fix the fwsec sb verification register.

This aligns with what open gpu does, the 0x15 hex is just to trick you.

Fixes: 176fdcbd ("drm/nouveau/gsp/r535: add support for booting GSP-RM")
Reviewed-by: Ben Skeggs <bskeggs@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240828023720.1596602-1-airlied@gmail.com

drivers/gpu/drm/nouveau/nvkm/subdev/gsp/fwsec.c

@@ -324,7 +324,7 @@ nvkm_gsp_fwsec_sb(struct nvkm_gsp *gsp)
 		return ret;
 
 	/* Verify. */
-	err = nvkm_rd32(device, 0x001400 + (0xf * 4)) & 0x0000ffff;
+	err = nvkm_rd32(device, 0x001400 + (0x15 * 4)) & 0x0000ffff;
 	if (err) {
 		nvkm_error(subdev, "fwsec-sb: 0x%04x\n", err);
 		return -EIO;