cx231xx: fix wrong usage of select in kconfig

VIDEO_CX231XX_ALSA depends on SND && SND_PCM,
but if we select it from VIDEO_CX231XX entry
it does not automatically select SND_PCM.
It causes build error:
ERROR: "snd_pcm_period_elapsed" [drivers/media/video/cx231xx/cx231xx-alsa.ko] undefined!

Documentation/kbuild/kconfig-language.txt:
Note:
select should be used with care. select will force a symbol to a value without visiting the dependencies. By abusing select you are able to select a symbol FOO even if FOO depends on BAR that is not set.

---

 drivers/media/video/cx231xx/Kconfig |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

index 9115654..85ae751 100644
@@ -6,7 +6,6 @@ config VIDEO_CX231XX
        select VIDEO_IR
        select VIDEOBUF_VMALLOC
        select VIDEO_CX25840
-       select VIDEO_CX231XX_ALSA
 
 	---help---
 	  This is a video4linux driver for Conexant 231xx USB based TV cards.