mfd: cros_ec: Allow building for ARM64

There are platforms using the ChromeOS embeded controller on ARM64 now,
so let's allow using this driver (without having to use COMPILE_TEST).

Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index aa1e7c3..cf7cbba 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -134,7 +134,7 @@
 	select MFD_CORE
 	select CHROME_PLATFORMS
 	select CROS_EC_PROTO
-	depends on X86 || ARM || COMPILE_TEST
+	depends on X86 || ARM || ARM64 || COMPILE_TEST
 	help
 	  If you say Y here you get support for the ChromeOS Embedded
 	  Controller (EC) providing keyboard, battery and power services.