spi: cadence-qspi: Add a flag for controllers without indirect access support

spi: cadence-qspi: Add a flag for controllers without indirect access support

Renesas RZ/N1 QSPI controllers embed the Cadence IP with some
limitations/simplifications. One of the is that only direct access is
supported, none of the registers related to indirect writes are
populated, so create a flag to avoid these accesses and make sure only
direct accessors are called.

Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
Tested-by: Santhosh Kumar K <s-k6@ti.com>
Link: https://patch.msgid.link/20260122-schneider-6-19-rc1-qspi-v4-11-f9c21419a3e6@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>