[ALSA] pcsp - Fix dependency in Kconfig

Added the proper dependency to Kconfig for snd-pcsp driver.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/drivers/Kconfig

@@ -7,6 +7,7 @@ menu "Generic devices"
 config SND_PCSP
 	tristate "Internal PC speaker support"
 	depends on X86_PC && HIGH_RES_TIMERS
+	depends on INPUT
 	help
 	  If you don't have a sound card in your computer, you can include a
 	  driver for the PC speaker which allows it to act like a primitive