drm/nouveau/bios: add some more signatures as seen on my gtx660

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/subdev/bios/image.c

@@ -38,6 +38,7 @@ nvbios_imagen(struct nouveau_bios *bios, struct nvbios_image *image)
 
 	switch ((data = nv_ro16(bios, image->base + 0x00))) {
 	case 0xaa55:
+	case 0xbb77:
 	case 0x4e56: /* NV */
 		break;
 	default:

drivers/gpu/drm/nouveau/core/subdev/bios/pcir.c

@@ -33,6 +33,7 @@ nvbios_pcirTe(struct nouveau_bios *bios, u32 base, u8 *ver, u16 *hdr)
 		data += base;
 		switch (nv_ro32(bios, data + 0x00)) {
 		case 0x52494350: /* PCIR */
+		case 0x53494752: /* RGIS */
 		case 0x5344504e: /* NPDS */
 			*hdr = nv_ro16(bios, data + 0x0a);
 			*ver = nv_ro08(bios, data + 0x0c);