soc: mediatek: mmsys: Specify HAS_IOMEM dependency for MTK_MMSYS

Because mtk-mmsys uses the 'devm_platform_ioremap_resource' function, it
should depend on HAS_IOMEM.

Fixes: cc65760 ("soc: mediatek: mmsys: Use devm_platform_ioremap_resource()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20201203121447.3366406-1-enric.balletbo@collabora.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/soc/mediatek/Kconfig

@@ -68,6 +68,7 @@ config MTK_SCPSYS_PM_DOMAINS
 config MTK_MMSYS
 	bool "MediaTek MMSYS Support"
 	default ARCH_MEDIATEK
+	depends on HAS_IOMEM
 	help
 	  Say yes here to add support for the MediaTek Multimedia
 	  Subsystem (MMSYS).