staging/easycap: fix build when SND is not enabled

Fix easycap build when CONFIG_SOUND is enabled but CONFIG_SND is
not enabled.

use choice construct to select between ALSA and OSS API binding

drivers/built-in.o: In function `easycap_usb_disconnect':
easycap_main.c:(.text+0x2aba20): undefined reference to `snd_card_free'
drivers/built-in.o: In function `easycap_alsa_probe':
(.text+0x2b784b): undefined reference to `snd_card_create'
drivers/built-in.o: In function `easycap_alsa_probe':
(.text+0x2b78fb): undefined reference to `snd_pcm_new'
drivers/built-in.o: In function `easycap_alsa_probe':
(.text+0x2b7916): undefined reference to `snd_pcm_set_ops'
drivers/built-in.o: In function `easycap_alsa_probe':
(.text+0x2b795b): undefined reference to `snd_card_register'
drivers/built-in.o: In function `easycap_alsa_probe':
(.text+0x2b79d8): undefined reference to `snd_card_free'
drivers/built-in.o: In function `easycap_alsa_probe':
(.text+0x2b7a78): undefined reference to `snd_card_free'
drivers/built-in.o: In function `easycap_alsa_complete':
(.text+0x2b7e68): undefined reference to `snd_pcm_period_elapsed'
drivers/built-in.o:(.data+0x2cae8): undefined reference to `snd_pcm_lib_ioctl'
Reported-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: R.M. Thomas <rmthomas@sciolus.org>
Signed-off-by: NTomas Winkler <tomas.winkler@intel.com>
Acked-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/easycap/Kconfig

 config EASYCAP
 	tristate "EasyCAP USB ID 05e1:0408 support"
-	depends on USB && VIDEO_DEV && SOUND
+	depends on USB && VIDEO_DEV && (SND || SOUND_OSS_CORE)
 
 	---help---
 	  This is an integrated audio/video driver for EasyCAP cards with
@@ -15,9 +15,25 @@ config EASYCAP
 	  To compile this driver as a module, choose M here: the
 	  module will be called easycap
 
+choice
+        prompt "Sound Interface"
+        depends on EASYCAP
+        default EASYCAP_SND
+	---help---
+
+config EASYCAP_SND
+        bool "ALSA"
+	depends on SND
+	select SND_PCM
+
+        ---help---
+          Say 'Y' if you want to use ALSA interface
+
+	  This will disable Open Sound System (OSS) binding.
+
 config EASYCAP_OSS
 	bool "OSS (DEPRECATED)"
-	depends on EASYCAP && SOUND_OSS_CORE
+	depends on SOUND_OSS_CORE
 
 	---help---
 	  Say 'Y' if you prefer Open Sound System (OSS) interface
@@ -26,6 +42,7 @@ config EASYCAP_OSS
 
 	  Once binding to ALSA interface will be stable this option will be
           removed.
+endchoice
 
 config EASYCAP_DEBUG
 	bool "Enable EasyCAP driver debugging"