spi: axi-spi-engine: Add SPI_CS_HIGH support

The AXI SPI Engine IP core v1.2 added support for SPI_CS_HIGH. This
provides the driver implementation to make use of this feature when
supported hardware is detected.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://msgid.link/r/20240508-spi-axi-spi-engine-add-spi_cs_high-support-v1-1-695dd8e45f00@baylibre.com


Signed-off-by: Mark Brown <broonie@kernel.org>