LoongArch: Fix cpu name after CPU-hotplug

Don't overwrite the SMBIOS-provided CPU name on coming back from CPU-
hotplug (including S3/S4) if it is already initialized.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/kernel/cpu-probe.c

@@ -187,7 +187,9 @@ static inline void cpu_probe_loongson(struct cpuinfo_loongarch *c, unsigned int
 	uint64_t *vendor = (void *)(&cpu_full_name[VENDOR_OFFSET]);
 	uint64_t *cpuname = (void *)(&cpu_full_name[CPUNAME_OFFSET]);
 
-	__cpu_full_name[cpu] = cpu_full_name;
+	if (!__cpu_full_name[cpu])
+		__cpu_full_name[cpu] = cpu_full_name;
+
 	*vendor = iocsr_read64(LOONGARCH_IOCSR_VENDOR);
 	*cpuname = iocsr_read64(LOONGARCH_IOCSR_CPUNAME);