mtd: spi-nor: add support for Gigadevice GD25LQ32

Tested against GD25LQ32D but the GD25LQ32C datasheet seems to be
identically feature-wise. Therefore dropping the suffix as it's
probably only indicating the die revision.

Signed-off-by: Klaus Goger <klaus.goger@theobroma-systems.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>