3.0.0-rc1 build failure when CONFIG_GPIO not set

CC [M] sound/soc/codecs/ak4641.o
sound/soc/codecs/ak4641.c: In function ‘ak4641_probe’:
sound/soc/codecs/ak4641.c:524:6: error: ‘GPIOF_OUT_INIT_LOW’ undeclared (first use in this function) sound/soc/codecs/ak4641.c:524:6: note: each undeclared identifier is reported only once for each function it appears in make[3]: *** [sound/soc/codecs/ak4641.o] Error 1
make[2]: *** [sound/soc/codecs] Error 2
make[1]: *** [sound/soc] Error 2
make: *** [sound] Error 2
make: *** Waiting for unfinished jobs....