platform: mips: cpu_hwmon: Disable driver on unsupported hardware

cpu_hwmon is unsupported on CPUs without loongson_chiptemp
register and csr.

Cc: [e-mail]
Signed-off-by: Jiaxun Yang <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

drivers/platform/mips/cpu_hwmon.c

···
 		csr_temp_enable = csr_readl(LOONGSON_CSR_FEATURES) &
 				  LOONGSON_CSRF_TEMP;
 
+	if (!csr_temp_enable && !loongson_chiptemp[0])
+		return -ENODEV;
+
 	nr_packages = loongson_sysconf.nr_cpus /
 		loongson_sysconf.cores_per_package;