[][kernel][7988][mt753x][split  patches to file5.4]

[Description]
Fix MT7988-fpga build failed by split some phy patch to file-5.4

[Release-log]
N/A

Change-Id: Ibb5c0da1d8af8d524baac9071eea1fee0ec7bd44
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6988291
diff --git a/target/linux/mediatek/files-5.4/drivers/net/phy/mtk/mt753x/mt753x_nl.c b/target/linux/mediatek/files-5.4/drivers/net/phy/mtk/mt753x/mt753x_nl.c
index cee89db..fa8e595 100644
--- a/target/linux/mediatek/files-5.4/drivers/net/phy/mtk/mt753x/mt753x_nl.c
+++ b/target/linux/mediatek/files-5.4/drivers/net/phy/mtk/mt753x/mt753x_nl.c
@@ -75,8 +75,10 @@
 		len = snprintf(buf, sizeof(buf),
 			       "id: %d, model: %s, node: %s\n",
 			       gsw->id, gsw->name, gsw->dev->of_node->name);
-		strncat(buff, buf, size - total);
-		total += len;
+		if (len == strlen(buf)) {
+			strncat(buff, buf, size - total);
+			total += len;
+		}
 	}
 
 	mt753x_put_gsw();