mtd: rawnand: intel: Remove unused nand_pa member from ebu_nand_cs

The nand_pa member from struct ebu_nand_cs is only written but never
read. Remove this unused and unneeded member.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220702231227.1579176-7-martin.blumenstingl@googlemail.com