mtd: spinand: gigadevice: Only one dummy byte in QUADIO

The datasheet only lists one dummy byte in the 0xEH operation for the
following chips:
* GD5F1GQ4xExxG
* GD5F1GQ4xFxxG
* GD5F1GQ4UAYIG
* GD5F4GQ4UAYIG

Fixes: c93c6132 ("mtd: spinand: add support for GigaDevice GD5FxGQ4xA")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Tested-by: Chuanhong Guo <gch981213@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200820165121.3192-2-hauke@hauke-m.de