mtd: maps: gpio-addr-flash: Convert to gpiod

Convert from legacy gpio API to gpiod.
Board files will have to use gpiod_lookup_tables.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Suggested-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>