ALSA: line6: Refer to manufacturer as "Line 6"

The correct spelling includes the space.  Fix this in strings and
comments that refer to the manufacturer.

Signed-off-by: Chris Rorvick <chris@rorvick.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/line6/playback.c b/sound/usb/line6/playback.c
index ec2384c..660094b 100644
--- a/sound/usb/line6/playback.c
+++ b/sound/usb/line6/playback.c
@@ -1,5 +1,5 @@
 /*
- * Line6 Linux USB driver - 0.9.1beta
+ * Line 6 Linux USB driver - 0.9.1beta
  *
  * Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at)
  *