spi: cadence-quadspi: Disable the SPI before reconfiguring

Observed random DMA timeout failures while doing back to back
transfers which involves switching the modes from DMA to NON-DMA.
This issue is observed while testing the OSPI+UBIFS file system test case
where rootfs is mounted from OSPI UBIFS partition.
To avoid this issue, disable the SPI before changing the configuration
from external DMA to NON-DMA and vice versa and reenable it after changing
the configuration.
As per the Cadence Octal SPI design specification, it is recommended to
disable the Octal-SPI enable bit before reconfiguring.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
Link: https://lore.kernel.org/r/20230320095931.2651714-3-sai.krishna.potthuri@amd.com


Signed-off-by: Mark Brown <broonie@kernel.org>