clocksource/drivers/sun4i: Add the COMPILE_TEST option

Increase the compilation test coverage by adding the COMPILE_TEST option.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 24a8d8d..67be8f4 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -71,8 +71,10 @@
 	  Enables the support for the Orion timer driver
 
 config SUN4I_TIMER
+	bool "Sun4i timer driver" if COMPILE_TEST
 	select CLKSRC_MMIO
-	bool
+	help
+	  Enables support for the Sun4i timer.
 
 config SUN5I_HSTIMER
 	select CLKSRC_MMIO