[ALSA] PCM midlevel & PCM OSS - make procfs & OSS plugin code optional

Modules: ALSA Core,PCM Midlevel,ALSA<-OSS emulation,USB generic driver

1) The verbose procfs code for the PCM midlevel and usb audio
   can be removed now (more patches will follow).
   CONFIG_SND_VERBOSE_PROCFS
2) The PCM OSS plugin system can be also compiled optionaly.
   CONFIG_SND_PCM_OSS_PLUGINS

Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/core/oss/linear.c

@@ -21,6 +21,9 @@
  */
 
 #include <sound/driver.h>
+
+#ifdef CONFIG_SND_PCM_OSS_PLUGINS
+
 #include <linux/time.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
@@ -156,3 +159,5 @@ int snd_pcm_plugin_build_linear(struct snd_pcm_substream *plug,
 	*r_plugin = plugin;
 	return 0;
 }
+
+#endif