mtd: spi-nor: Added dual parallel support to gqspi driver

Added the dual parallel configuration support to the gqspi driver.

Signed-off-by: Anurag Kumar Vulisha <anuragku@xilinx.com>
Reviewed-by: Harini Katakam <harinik@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>