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: cc6576029aed ("soc: mediatek: mmsys: Use devm_platform_ioremap_resource()")
Reported-by: kernel test robot <[e-mail]>
Signed-off-by: Enric Balletbo i Serra <[e-mail]>
Signed-off-by: Matthias Brugger <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnd Bergmann <[e-mail]>

drivers/soc/mediatek/Kconfig

···
 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).