ALSA: Move some headers to local directories from include/sound

This is a bit clean up of public sound header directory.
Some header files in include/sound aren't really necessary to be
located there but can be moved to their local directories gracefully.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/trident/trident_memory.c b/sound/pci/trident/trident_memory.c
index f9779e2..3102a57 100644
--- a/sound/pci/trident/trident_memory.c
+++ b/sound/pci/trident/trident_memory.c
@@ -29,7 +29,7 @@
 #include <linux/mutex.h>
 
 #include <sound/core.h>
-#include <sound/trident.h>
+#include "trident.h"
 
 /* page arguments of these two macros are Trident page (4096 bytes), not like
  * aligned pages in others