clocksource/drivers/armada-370-xp: Add the COMPILE_TEST option

Increase the compilation test coverage by adding the COMPILE_TEST option.

Due to the non portable 'delay' code, the compilation is restricted to the
ARM architecture only.
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/Kconfig

@@ -46,8 +46,11 @@ config ROCKCHIP_TIMER
 	  Enables the support for the rockchip timer driver.
 
 config ARMADA_370_XP_TIMER
-	bool
+	bool "Armada 370 and XP timer driver" if COMPILE_TEST
+	depends on ARM
 	select CLKSRC_OF
+	help
+	  Enables the support for the Armada 370 and XP timer driver.
 
 config MESON6_TIMER
 	bool