iio: dac: adi-axi-dac: add platform dependencies

Being this device a soft core, it's only supported on some/specific
platforms. Hence add proper dependencies for the supported platforms.
Also add COMPILE_TEST to increase the build coverage.
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240604-dev-axi-dac-kconfig-v1-1-99ccd03938d1@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/Kconfig

@@ -149,6 +149,7 @@ config AD9739A
 
 config ADI_AXI_DAC
 	tristate "Analog Devices Generic AXI DAC IP core driver"
+	depends on MICROBLAZE || NIOS2 || ARCH_ZYNQ || ARCH_ZYNQMP || ARCH_INTEL_SOCFPGA || COMPILE_TEST
 	select IIO_BUFFER
 	select IIO_BUFFER_DMAENGINE
 	select REGMAP_MMIO