Add support for ISSI is25lp256 spi nor flash.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Angelo Dureghello <angelo@sysam.it>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>