spi: cadence-qspi: allow FIFO depth detection

spi: cadence-qspi: allow FIFO depth detection

If FIFO depth DT property is provided, check it matches what hardware
reports and warn otherwise. Else, use hardware provided value.

Hardware exposes FIFO depth indirectly because
CQSPI_REG_SRAMPARTITION is partially read-only.

Move probe cqspi->ddata assignment prior to cqspi_of_get_pdata() call.

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20240423-cdns-qspi-mbly-v4-1-3d2a7b535ad0@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>