rtc: Add module.h to implicit users in drivers/rtc

The module.h was implicitly everywhere, but when we clean
that up, the implicit users will compile fail; fix them up
in advance.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/rtc/rtc-pcf2123.c b/drivers/rtc/rtc-pcf2123.c
index 71bab0e..2ee3bbf 100644
--- a/drivers/rtc/rtc-pcf2123.c
+++ b/drivers/rtc/rtc-pcf2123.c
@@ -42,6 +42,7 @@
 #include <linux/slab.h>
 #include <linux/rtc.h>
 #include <linux/spi/spi.h>
+#include <linux/module.h>
 
 #define DRV_VERSION "0.6"