[MTD] Fix module refcounting in NAND board drivers.

The _board_ driver needs to be mtd->owner, and it in turn pins the
nand.ko module. Fix them all to actually do that, and fix nand.ko not to
overwrite it -- and also to check that the caller sets it, if the caller
is a module.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/nand/edb7312.c

@@ -148,6 +148,7 @@ static int __init ep7312_init(void)
 
 	/* Link the private data with the MTD structure */
 	ep7312_mtd->priv = this;
+	ep7312_mtd->owner = THIS_MODULE;
 
 	/*
 	 * Set GPIO Port B control register so that the pins are configured