sound: samsung: Fix compile problem

This patch fixes the compile error as below.

sound/soc/samsung/hkdk_max98090.c:217:18: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
sound/soc/samsung/hkdk_max98090.c:249:12: error: ‘hkdk_max98090_driver_probe’ undeclared here (not in a function)
sound/soc/samsung/hkdk_max98090.c:210:28: warning: ‘snd_soc_hkdk_max98090’ defined but not used [-Wunused-variable]