spi: axi-spi-engine: use devm_spi_alloc_host()

This modifies the AXI SPI Engine driver to use devm_spi_alloc_host()
instead of spi_alloc_host() to simplify the code a bit.

In addition to simplifying the error paths in the probe function, we
can also remove spi_controller_get/put() calls in the remove function
since devm_spi_alloc_host() sets a flag to no longer decrement the
controller reference count in the spi_unregister_controller() function.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231117-axi-spi-engine-series-1-v1-4-cc59db999b87@baylibre.com


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