ALSA: cs5535audio: Also needed on MIPS

The CS5536 companion chipset is not only used on 32-bit x86 systems as
I originally thought, it is also used on MIPS Loongson/Lemote 2
systems. So let the snd-cs5535audio driver be built on MIPS too.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>