iio:adc:cc10001_adc: fix Kconfig dependency

The Cosmic Circuits 10001 ADC driver depends on HAS_IOMEM, HAVE_CLK and
REGULATOR together, not just any of these.

Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>