gusextreme depends on opl3 support. Add the approriate select to Kconfig.
Also remove the unnecessary hwdep select.
Relevant build errors:
ERROR: "snd_opl3_hwdep_new" [sound/isa/gus/snd-gusextreme.ko] undefined!
ERROR: "snd_opl3_create" [sound/isa/gus/snd-gusextreme.ko] undefined!
Signed-off-by: Ville Syrjala <syrjala@sci.fi>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
 
 config SND_GUSEXTREME
        tristate "Gravis UltraSound Extreme"
-       select SND_HWDEP
+       select SND_OPL3_LIB
        select SND_MPU401_UART
        select SND_PCM
        help