dmaengine: SF_PDMA depends on HAS_IOMEM

When CONFIG_HAS_IOMEM is not set/enabled, certain iomap() family
functions [including ioremap(), devm_ioremap(), etc.] are not
available.
Drivers that use these functions should depend on HAS_IOMEM so that
they do not cause build errors.

Mends this build error:
s390-linux-ld: drivers/dma/sf-pdma/sf-pdma.o: in function `sf_pdma_probe':
sf-pdma.c:(.text+0x1668): undefined reference to `devm_ioremap_resource'

Fixes: 6973886a ("dmaengine: sf-pdma: add platform DMA support for HiFive Unleashed A00")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Green Wan <green.wan@sifive.com>
Cc: Vinod Koul <vkoul@kernel.org>
Cc: dmaengine@vger.kernel.org
Link: https://lore.kernel.org/r/20210522021313.16405-4-rdunlap@infradead.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/sf-pdma/Kconfig

 config SF_PDMA
 	tristate "Sifive PDMA controller driver"
+	depends on HAS_IOMEM
 	select DMA_ENGINE
 	select DMA_VIRTUAL_CHANNELS
 	help