snd-pcsp: depend on CONFIG_EXPERIMENTAL

Considering all the feedbacks I got, depending snd-pcsp on
CONFIG_EXPERIMENTAL looks like the only safe way to get out
of all the troubles at one go. :)
Signed-off-by: Stas Sergeev <stsp@aknet.ru>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/Kconfig

@@ -8,6 +8,7 @@ config SND_PCSP
 	tristate "PC-Speaker support (READ HELP!)"
 	depends on PCSPKR_PLATFORM && X86_PC && HIGH_RES_TIMERS
 	depends on INPUT
+	depends on EXPERIMENTAL
 	depends on SND
 	select SND_PCM
 	help