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: NBrian Norris <briannorris@chromium.org>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -134,7 +134,7 @@ config MFD_CROS_EC
 	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.