build: fix GOARCH for loongarch64 (Makefile)

uname gives loongarch64 target value while go has
loong64 target instead. Without the fix `make
install` can't find correct executable since it
looks into bin/loongarch64 instead of bin/loong64

Makefile

@@ -6,6 +6,8 @@ ifeq ($(GOARCH),x86_64)
 	GOARCH=amd64
 else ifeq ($(GOARCH),aarch64)
 	GOARCH=arm64
+else ifeq ($(GOARCH),loongarch64)
+	GOARCH=loong64
 else ifeq ($(patsubst armv%,arm,$(GOARCH)),arm)
 	GOARCH=arm
 else ifeq ($(patsubst i%86,386,$(GOARCH)),386)