mtd: hyperbus: Provide per device private pointer

Provide per device private pointer that can be used by controller
drivers to store device specific private data.

Signed-off-by: Vignesh Raghavendra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

include/linux/mtd/hyperbus.h

···
  * @mtd: pointer to MTD struct
  * @ctlr: pointer to HyperBus controller struct
  * @memtype: type of memory device: HyperFlash or HyperRAM
+ * @priv: pointer to controller specific per device private data
  */
 
 struct hyperbus_device {
···
 	struct mtd_info *mtd;
 	struct hyperbus_ctlr *ctlr;
 	enum hyperbus_memtype memtype;
+	void *priv;
 };
 
 /**