MIPS: Loongson: Cleanup CONFIG_LOONGSON_SUSPEND.

MIPS: Loongson: Cleanup CONFIG_LOONGSON_SUSPEND.

Now LOONGSON_CHIPCFG register definition doesn't depend on CPUFREQ any
more, so CPU_SUPPORTS_CPUFREQ is no longer needed for suspend/resume.
Remove CONFIG_LOONGSON_SUSPEND and use CONFIG_SUSPEND instead.

Signed-off-by: Huacai Chen <[email protected]>
Cc: John Crispin <[email protected]>
Cc: Steven J. Hill <[email protected]>
Cc: Fuxin Zhang <[email protected]>
Cc: Zhangjin Wu <[email protected]>
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/11274/
Signed-off-by: Ralf Baechle <[email protected]>