ALSA: core - Define llseek fops

Set no_llseek to llseek file ops of each sound component (but for hwdep).
This avoids the implicit BKL invocation via generic_file_llseek() used
as default when fops.llseek is NULL.

Also call nonseekable_open() at each open ops to ensure the file flags
have no seek bit.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 82d4e33..5c8c7df 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -2379,6 +2379,10 @@
 	int nonblock;
 	wait_queue_t wait;
 
+	err = nonseekable_open(inode, file);
+	if (err < 0)
+		return err;
+
 	pcm = snd_lookup_oss_minor_data(iminor(inode),
 					SNDRV_OSS_DEVICE_TYPE_PCM);
 	if (pcm == NULL) {
@@ -2977,6 +2981,7 @@
 	.write =	snd_pcm_oss_write,
 	.open =		snd_pcm_oss_open,
 	.release =	snd_pcm_oss_release,
+	.llseek =	no_llseek,
 	.poll =		snd_pcm_oss_poll,
 	.unlocked_ioctl =	snd_pcm_oss_ioctl,
 	.compat_ioctl =	snd_pcm_oss_ioctl_compat,