mfd: Add module.h to the implicit drivers/mfd users

With the pending module.h cleanup, these files will fail to compile,
unless they explicitly call out the include of this file.

[omap-usb-host addition courtesy of Anand Gadiyar <gadiyar@ti.com>]

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index 0902523..0f59228 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -17,6 +17,7 @@
 #include <linux/mfd/core.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
+#include <linux/module.h>
 
 int mfd_cell_enable(struct platform_device *pdev)
 {