timekeeping: Switch HAS_PERSISTENT_CLOCK to ALWAYS_USE_PERSISTENT_CLOCK

Jason pointed out the HAS_PERSISTENT_CLOCK name isn't
quite accurate for the config, as some systems may have
the persistent_clock in some cases, but not always.

So change the config name to the more clear
ALWAYS_USE_PERSISTENT_CLOCK.

Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/include/linux/time.h b/include/linux/time.h
index 369b6e3..476e1d7 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -117,7 +117,7 @@
 
 extern bool persistent_clock_exist;
 
-#ifdef CONFIG_HAS_PERSISTENT_CLOCK
+#ifdef ALWAYS_USE_PERSISTENT_CLOCK
 #define has_persistent_clock()	true
 #else
 static inline bool has_persistent_clock(void)