media: dvb-frontends/mxl5xx: cleanup and fix licensing boilerplates

mxl5xx.h doesn't carry any licensing boilerplate at all right now, so copy
the boilerplate over from the main driver file mxl5xx.c. Also, mxl5xx_defs
is missing a part of the licensing boilerplate text, so add it.

[[e-mail]: kept only the part of this patch that copied
the license from mxl5xx.c into mxl5xx.h]
Cc: Ralph Metzler <[e-mail]>
Cc: Manfred Voelkel <[e-mail]>
Signed-off-by: Daniel Scheller <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/dvb-frontends/mxl5xx.c

···
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
- *
  */
 
 #include <linux/kernel.h>

drivers/media/dvb-frontends/mxl5xx.h

···
+/*
+ * Driver for the MaxLinear MxL5xx family of tuners/demods
+ *
+ * Copyright (C) 2014-2015 Ralph Metzler <[e-mail]>
+ *                         Marcus Metzler <[e-mail]>
+ *                         developed for Digital Devices GmbH
+ *
+ * based on code:
+ * Copyright (c) 2011-2013 MaxLinear, Inc. All rights reserved
+ * which was released under GPL V2
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
 #ifndef _MXL5XX_H_
 #define _MXL5XX_H_