mtd: rawnand: atmel: Allow selection of this driver when COMPILE_TEST=y

It just makes NAND maintainers' life easier by allowing them to
compile-test this driver without having ARCH_AT91 enabled.

We also need to add a dependency on HAS_IOMEM to make sure the driver
compiles correctly.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/Kconfig

@@ -277,7 +277,8 @@ config MTD_NAND_CS553X
 
 config MTD_NAND_ATMEL
 	tristate "Support for NAND Flash / SmartMedia on AT91"
-	depends on ARCH_AT91
+	depends on ARCH_AT91 || COMPILE_TEST
+	depends on HAS_IOMEM
 	select MFD_ATMEL_SMC
 	help
 	  Enables support for NAND Flash / Smart Media Card interface