Since imx7d_adc_remove() does exactly the same thing as
imx7d_adc_suspend() we can use the latter together with
devm_add_action_or_reset() to simplify the former. Rename
imx7d_adc_suspend() to imx7d_adc_disable() for clarity while at it.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: Chris Healy <cphealy@gmail.com>
Cc: linux-iio@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>