dmaengine: drivers: Kconfig: add HAS_IOMEM dependency to DW_AXI_DMAC

If HAS_IOMEM is not defined and DW_AXI_DMAC is enabled under COMPILE_TEST,
the build fails with the following error:
dw-axi-dmac-platform.c:(.text+0xc4): undefined reference to
`devm_ioremap_resource'
Link: https://www.spinics.net/lists/dmaengine/msg25188.html



Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sia Jee Heng <jee.heng.sia@intel.com>
Link: https://lore.kernel.org/r/20210125013255.25799-13-jee.heng.sia@intel.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>