md: Add module.h to all files using it implicitly

A pending cleanup will mean that module.h won't be implicitly
everywhere anymore.  Make sure the modular drivers in md dir
are actually calling out for <module.h> explicitly in advance.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

drivers/md/dm-service-time.c

@@ -12,6 +12,7 @@
 #include "dm-path-selector.h"
 
 #include <linux/slab.h>
+#include <linux/module.h>
 
 #define DM_MSG_PREFIX	"multipath service-time"
 #define ST_MIN_IO	1