reset: reset-mtmips: add DM_FLAG_PRE_RELOC flag

Add DM_FLAG_PRE_RELOC flag for reset-mtmips to make sure this driver can
be probed before relocation even if u-boot,dm-pre-reloc is not present
in the dts.

Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
diff --git a/drivers/reset/reset-mtmips.c b/drivers/reset/reset-mtmips.c
index 848425a..4e71d52 100644
--- a/drivers/reset/reset-mtmips.c
+++ b/drivers/reset/reset-mtmips.c
@@ -82,4 +82,5 @@
 	.probe = mtmips_reset_probe,
 	.priv_auto	= sizeof(struct mtmips_reset_priv),
 	.ops = &mtmips_reset_ops,
+	.flags = DM_FLAG_PRE_RELOC,
 };