drm/i2c/ch7006: Don't use POWER_LEVEL_FULL_POWER_OFF on early chip versions.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/i2c/ch7006_mode.c b/drivers/gpu/drm/i2c/ch7006_mode.c
index e447dfb..c860f24 100644
--- a/drivers/gpu/drm/i2c/ch7006_mode.c
+++ b/drivers/gpu/drm/i2c/ch7006_mode.c
@@ -316,7 +316,10 @@
 		}
 
 	} else {
-		*power |= bitfs(CH7006_POWER_LEVEL, FULL_POWER_OFF);
+		if (priv->chip_version >= 0x20)
+			*power |= bitfs(CH7006_POWER_LEVEL, FULL_POWER_OFF);
+		else
+			*power |= bitfs(CH7006_POWER_LEVEL, POWER_OFF);
 	}
 }