spi: zynqmp_gqspi: Add support for IO mode

Add support for io-mode transfers. This is necessary for UBIFS to work
properly with spi-nor devices. The driver will work in IO mode when
"has-io-mode" is passed from device tree instead of DMA.

Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@amd.com>
Link: https://lore.kernel.org/r/20220825125906.11581-4-ashok.reddy.soma@amd.com


Signed-off-by: Michal Simek <michal.simek@amd.com>