iio: adc: adi-axi-adc: add proper Kconfig dependencies

The ADI AXI ADC driver requires IO mem access and OF to work. This change
adds these dependencies to the Kconfig symbol of the driver.

This was also found via the lkp bot, as the
devm_platform_ioremap_resource() symbol was not found at link-time on the
S390 architecture.

Fixes: ef040706 ("iio: adc: adi-axi-adc: add support for AXI ADC IP core")
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210210105044.48914-1-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/Kconfig

@@ -266,6 +266,8 @@ config ADI_AXI_ADC
 	select IIO_BUFFER
 	select IIO_BUFFER_HW_CONSUMER
 	select IIO_BUFFER_DMAENGINE
+	depends on HAS_IOMEM
+	depends on OF
 	help
 	  Say yes here to build support for Analog Devices Generic
 	  AXI ADC IP core. The IP core is used for interfacing with