timer: MediaTek: add timer driver for MediaTek SoCs

This patch adds clock source and clock event for the timer found
on the Mediatek SoCs.

Tested-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index d0cfc35..b0e6f32 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -160,4 +160,11 @@
 	help
 	  Select this to enable Time-Stamp Counter (TSC) timer for x86.
 
+config MTK_TIMER
+	bool "MediaTek timer support"
+	depends on TIMER
+	help
+	  Select this to enable support for the timer found on
+	  MediaTek devices.
+
 endmenu