mtd: spinand: gigadevice: add support for GD5F{2, 4}GQ5xExxG

Add support for:
 GD5F2GQ5{U,R}ExxG
 GD5F4GQ6{U,R}ExxG

These chips uses 4 dummy bytes for quad io and 2 dummy bytes for dual io.
Besides that and memory layout, they are identical to their 1G variant.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220320100001.247905-5-gch981213@gmail.com