firmware loader: fix another compile warning with PM_SLEEP unset

This patch fixes another compiling warning with PM_SLEEP unset:

drivers/base/firmware_class.c:221:29: warning: 'fw_lookup_buf' defined
but not used [-Wunused-function]

This time I do build kernel with both PM_SLEEP set and unset, and no
warning found any more with the patch.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/firmware_class.c

@@ -218,18 +218,6 @@ static int fw_lookup_and_allocate_buf(const char *fw_name,
 	return tmp ? 0 : -ENOMEM;
 }
 
-static struct firmware_buf *fw_lookup_buf(const char *fw_name)
-{
-	struct firmware_buf *tmp;
-	struct firmware_cache *fwc = &fw_cache;
-
-	spin_lock(&fwc->lock);
-	tmp = __fw_lookup_buf(fw_name);
-	spin_unlock(&fwc->lock);
-
-	return tmp;
-}
-
 static void __fw_free_buf(struct kref *ref)
 {
 	struct firmware_buf *buf = to_fwbuf(ref);
@@ -1280,6 +1268,18 @@ static int cache_firmware(const char *fw_name)
 	return ret;
 }
 
+static struct firmware_buf *fw_lookup_buf(const char *fw_name)
+{
+	struct firmware_buf *tmp;
+	struct firmware_cache *fwc = &fw_cache;
+
+	spin_lock(&fwc->lock);
+	tmp = __fw_lookup_buf(fw_name);
+	spin_unlock(&fwc->lock);
+
+	return tmp;
+}
+
 /**
  * uncache_firmware - remove one cached firmware image
  * @fw_name: the firmware image name