spi: cadence-quadspi: Update the read timeout based on the length

commit 62a31e763d966d8d1e4c25e8cdec16ecff775e6b from
https://github.com/Xilinx/linux-xlnx.git

 xlnx_rebase_v6.1

When performing a indirect read via external DMA the timeout for
completion is set equal to the read length instead of fixed timeout value.
For reads larger than 500 bytes, the timeout will continue to be
equal to the read length whereas for a small read like the Read Status
Register command, the timeout would be 1 or 2 milliseconds. This is not
enough to cover the overhead needed in setting up DMA, in that case make
sure the timeout is at least 500ms to allow DMA to finish. This solution
is inline with the timeout used for Direct read via DMA.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
State: pending
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>