sound: use non-racy method for /proc/driver/snd-page-alloc creation

Use proc_create() to make sure that ->proc_fops be setup before gluing PDE to
main tree.

Signed-off-by: Denis V. Lunev <[e-mail]>
Cc: Alexey Dobriyan <[e-mail]>
Cc: "Eric W. Biederman" <[e-mail]>
Cc: Jaroslav Kysela <[e-mail]>
Cc: Takashi Iwai <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

sound/core/memalloc.c

···
 static int __init snd_mem_init(void)
 {
 #ifdef CONFIG_PROC_FS
-	snd_mem_proc = create_proc_entry(SND_MEM_PROC_FILE, 0644, NULL);
-	if (snd_mem_proc)
-		snd_mem_proc->proc_fops = &snd_mem_proc_fops;
+	snd_mem_proc = proc_create(SND_MEM_PROC_FILE, 0644, NULL,
+				   &snd_mem_proc_fops);
 #endif
 	return 0;
 }