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-ds1305.c b/drivers/rtc/rtc-ds1305.c
index 57fbcc1..3a33b1f 100644
--- a/drivers/rtc/rtc-ds1305.c
+++ b/drivers/rtc/rtc-ds1305.c
@@ -17,6 +17,7 @@
 
 #include <linux/spi/spi.h>
 #include <linux/spi/ds1305.h>
+#include <linux/module.h>
 
 
 /*