staging:iio:ad799x fix typo in copyright message

Fix a typo in the copyright message.
Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/adc/ad799x_core.c

 /*
  * iio/adc/ad799x.c
- * Copyright (C) 2010-1011 Michael Hennerich, Analog Devices Inc.
+ * Copyright (C) 2010-2011 Michael Hennerich, Analog Devices Inc.
  *
  * based on iio/adc/max1363
  * Copyright (C) 2008-2010 Jonathan Cameron