sound: Add export.h for THIS_MODULE/EXPORT_SYMBOL where needed

These aren't modules, but they do make use of these macros, so
they will need export.h to get that definition.  Previously,
they got it via the implicit module.h inclusion.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/sound/pci/hda/hda_beep.c b/sound/pci/hda/hda_beep.c
index 29714c8..60738e5 100644
--- a/sound/pci/hda/hda_beep.c
+++ b/sound/pci/hda/hda_beep.c
@@ -23,6 +23,7 @@
 #include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
+#include <linux/export.h>
 #include <sound/core.h>
 #include "hda_beep.h"
 #include "hda_local.h"
diff --git a/sound/pci/hda/hda_generic.c b/sound/pci/hda/hda_generic.c
index a63c54d..431bf86 100644
--- a/sound/pci/hda/hda_generic.c
+++ b/sound/pci/hda/hda_generic.c
@@ -22,6 +22,7 @@
 
 #include <linux/init.h>
 #include <linux/slab.h>
+#include <linux/export.h>
 #include <sound/core.h>
 #include "hda_codec.h"
 #include "hda_local.h"
diff --git a/sound/pci/hda/hda_hwdep.c b/sound/pci/hda/hda_hwdep.c
index 72e5885..a6d5459 100644
--- a/sound/pci/hda/hda_hwdep.c
+++ b/sound/pci/hda/hda_hwdep.c
@@ -26,6 +26,7 @@
 #include <linux/ctype.h>
 #include <linux/string.h>
 #include <linux/firmware.h>
+#include <linux/export.h>
 #include <sound/core.h>
 #include "hda_codec.h"
 #include "hda_local.h"