spi: axi-spi-engine: return void from spi_engine_compile_message()

In the AXI SPI Engine driver, the spi_engine_compile_message() function
does not return any error and none of the callers check the return
value. So we can change the return type to void and drop the return 0.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20231204-axi-spi-engine-series-2-v1-1-063672323fce@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: dlech

drivers/spi/spi-axi-spi-engine.c

@@ -218,7 +218,7 @@ static void spi_engine_gen_cs(struct spi_engine_program *p, bool dry,
 	spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_ASSERT(1, mask));
 }
 
-static int spi_engine_compile_message(struct spi_engine *spi_engine,
+static void spi_engine_compile_message(struct spi_engine *spi_engine,
 	struct spi_message *msg, bool dry, struct spi_engine_program *p)
 {
 	struct spi_device *spi = msg->spi;
@@ -273,8 +273,6 @@ static int spi_engine_compile_message(struct spi_engine *spi_engine,
 
 	if (!keep_cs)
 		spi_engine_gen_cs(p, dry, spi, false);
-
-	return 0;
 }
 
 static void spi_engine_xfer_next(struct spi_message *msg,