mtd: spinand: gigadevice: Add support for GD5F4GQ4xC

This adds support for the following 4GiB chips:
GD5F4GQ4RCYIG 1.8V
GD5F4GQ4UCYIG 3.3V

The datasheet can be found here:
https://www.novitronic.ch/sixcms/media.php/2/DS-00173-GD5F4GQ4xCxIG-Rev1.574695.pdf



The GD5F4GQ4UCYIGT (3.3V) version is used on the Imagination
Technologies Creator Ci40 (Marduk), the 1.8V version was not tested.

This device only works in single SPI mode and not in dual or quad mode
for me on this board.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200820165121.3192-4-hauke@hauke-m.de