V4L/DVB: af9013: fix comments

Fix comments. It is demodulator driver not DVB USB -bridge.
Signed-off-by: NAntti Palosaari <crope@iki.fi>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/frontends/af9013.c

 /*
- * DVB USB Linux driver for Afatech AF9015 DVB-T USB2.0 receiver
+ * Afatech AF9013 demodulator driver
  *
  * Copyright (C) 2007 Antti Palosaari <crope@iki.fi>
  *

drivers/media/dvb/frontends/af9013.h

 /*
- * DVB USB Linux driver for Afatech AF9015 DVB-T USB2.0 receiver
+ * Afatech AF9013 demodulator driver
  *
  * Copyright (C) 2007 Antti Palosaari <crope@iki.fi>
  *

drivers/media/dvb/frontends/af9013_priv.h

 /*
- * DVB USB Linux driver for Afatech AF9015 DVB-T USB2.0 receiver
+ * Afatech AF9013 demodulator driver
  *
  * Copyright (C) 2007 Antti Palosaari <crope@iki.fi>
  *