MIPS: Loongson: Use CONFIG_NR_CPUS_DEFAULT_64 to support more CPUs

When I update the mainline kernel on the Loongson 2-way platform which
has 8 CPUs, it only shows 4 CPUs due to NR_CPUS is 4, this is obviously
wrong.

In order to support more CPUs on the Loongson platform, it is better
to use CONFIG_NR_CPUS_DEFAULT_64 instead of CONFIG_NR_CPUS_DEFAULT_4
to specify the maximum number of CPUs which the kernel will support.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/Kconfig

@@ -475,7 +475,7 @@ config MACH_LOONGSON64
 	select ISA
 	select I8259
 	select IRQ_MIPS_CPU
-	select NR_CPUS_DEFAULT_4
+	select NR_CPUS_DEFAULT_64
 	select USE_GENERIC_EARLY_PRINTK_8250
 	select SYS_HAS_CPU_LOONGSON64
 	select SYS_HAS_EARLY_PRINTK