mtd: spi-nor: core: disable Octal DTR mode on suspend.

On resume, the init procedure will be run that will re-enable it.

Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20201005153138.6437-14-p.yadav@ti.com