spi: zynqmp_qspi: Workaround for small data cache issue

Cache related issues are seen with small sized data reads.
Due to this, proper data is not read. Also some times sf probe
fails randomly. To workaround this issue, invalidate dcache after read DMA
is triggered.

Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@amd.com>
Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Link: https://lore.kernel.org/r/20230915031759.28889-3-venkatesh.abbarapu@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>