mtd: rawnand: Add support for manufacturer specific lock/unlock operation

Add nand_lock() & nand_unlock() for manufacturer specific lock & unlock
operation while the device supports Block Portection function.

Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/1583220084-10890-2-git-send-email-masonccyang@mxic.com.tw