ALSA: oss: Remove unused declarations

These functions is never implemented and used.

Signed-off-by: Yue Haibing <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/core/oss/pcm_plugin.h

···
                          size_t extra,
                          struct snd_pcm_plugin **ret);
 int snd_pcm_plugin_free(struct snd_pcm_plugin *plugin);
-int snd_pcm_plugin_clear(struct snd_pcm_plugin **first);
 int snd_pcm_plug_alloc(struct snd_pcm_substream *plug, snd_pcm_uframes_t frames);
 snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *handle, snd_pcm_uframes_t drv_size);
 snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *handle, snd_pcm_uframes_t clt_size);
···
 		      size_t dst_offset,
 		      size_t samples, snd_pcm_format_t format);
 
-void *snd_pcm_plug_buf_alloc(struct snd_pcm_substream *plug, snd_pcm_uframes_t size);
-void snd_pcm_plug_buf_unlock(struct snd_pcm_substream *plug, void *ptr);
 #else
 
 static inline snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *handle, snd_pcm_uframes_t drv_size) { return drv_size; }