mtd: core: call _get_device() with the master MTD

__get_mtd_device() calls the master's _get_device() callback with mtd,
which may be a partition. __put_mtd_device() passes the master.

This breaks gluebi partitions because gluebi_get_device() uses
container_of() and therefore requires the master MTD. Pass the master
to _get_device(), matching _put_device().

Fixes: 46b5889cc2 ("mtd: implement proper partition handling")
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Karl Mehltretter <[email protected]>
Signed-off-by: Miquel Raynal <[email protected]>

drivers/mtd/mtdcore.c

@@ -1333,7 +1333,7 @@ int __get_mtd_device(struct mtd_info *mtd)
 	int err;
 
 	if (master->_get_device) {
-		err = master->_get_device(mtd);
+		err = master->_get_device(master);
 		if (err)
 			return err;
 	}