drm/nouveau/bios/volt: Parse min and max for Version 0x40

This is according to what we have in nvbios.

Fixes "ERROR: Can't get value of subfeature in0_min: Can't read" errors
in sensors for some GPUs.
Signed-off-by: Karol Herbst <karolherbst@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/bios/volt.c

@@ -93,9 +93,9 @@ nvbios_volt_parse(struct nvkm_bios *bios, u8 *ver, u8 *hdr, u8 *cnt, u8 *len,
 		info->step    = nvbios_rd16(bios, volt + 0x08);
 		info->vidmask = nvbios_rd08(bios, volt + 0x0b);
 		info->ranged  = true; /* XXX: find the flag byte */
-		/*XXX*/
-		info->min     = 0;
-		info->max     = info->base;
+		info->min     = min(info->base,
+				    info->base + info->step * info->vidmask);
+		info->max     = nvbios_rd32(bios, volt + 0x0e);
 		break;
 	case 0x50:
 		info->min     = nvbios_rd32(bios, volt + 0x0a);