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>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 266e82e..23435fa 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -44,6 +44,7 @@
 #include <linux/hdreg.h>
 #include <linux/proc_fs.h>
 #include <linux/random.h>
+#include <linux/module.h>
 #include <linux/reboot.h>
 #include <linux/file.h>
 #include <linux/compat.h>