spi: axi-spi-engine: support SPI_MULTI_LANE_MODE_STRIPE

spi: axi-spi-engine: support SPI_MULTI_LANE_MODE_STRIPE

Add support for SPI_MULTI_LANE_MODE_STRIPE to the AXI SPI engine driver.

The v2.0.0 version of the AXI SPI Engine IP core supports multiple
lanes. This can be used with SPI_MULTI_LANE_MODE_STRIPE to support
reading from simultaneous sampling ADCs that have a separate SDO line
for each analog channel. This allows reading all channels at the same
time to increase throughput.

Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20260123-spi-add-multi-bus-support-v6-7-12af183c06eb@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>