iio: dac: dpot: Drop dependency on OF

Nothing in this driver depends on OF firmware 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/20220413190632.30365-1-andriy.shevchenko@linux.intel.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/Kconfig

@@ -285,7 +285,6 @@ config CIO_DAC
 
 config DPOT_DAC
 	tristate "DAC emulation using a DPOT"
-	depends on OF
 	help
 	  Say yes here to build support for DAC emulation using a digital
 	  potentiometer.