staging: iio: lpc32xx-adc: Remove driver conflict due to device tree

Previously, the touchscreen and ADC drivers of the LPC32xx SoC had a Kconfig
conflict declared because they use the same hardware. Upon the introduction of
device tree support in both drivers, the conflict must be removed to enable
the same kernel to support different hardware (configured via the device tree).

Signed-off-by: Roland Stigge <stigge@antcom.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>