iio: adc: envelope-detector: Drop dependency on OF

Nothing in this driver depends on OF so drop the dependency
to remove the false impression such a dependency exists.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220530181313.2789-1-andriy.shevchenko@linux.intel.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/Kconfig

@@ -417,7 +417,6 @@ config DLN2_ADC
 
 config ENVELOPE_DETECTOR
 	tristate "Envelope detector using a DAC and a comparator"
-	depends on OF
 	help
 	  Say yes here to build support for an envelope detector using a DAC
 	  and a comparator.